A Scanner breaks its input into tokens using a
* delimiter pattern, which by default matches whitespace. The resulting
* tokens may then be converted into values of different types using the
* various next methods.
*
*
For example, this code allows a user to read a number from * System.in: *
{@code
* Scanner sc = new Scanner(System.in);
* int i = sc.nextInt();
* }As another example, this code allows long types to be
* assigned from entries in a file myNumbers:
*
{@code
* Scanner sc = new Scanner(new File("myNumbers"));
* while (sc.hasNextLong()) {
* long aLong = sc.nextLong();
* }
* }The scanner can also use delimiters other than whitespace. This * example reads several items in from a string: *
{@code
* String input = "1 fish 2 fish red fish blue fish";
* Scanner s = new Scanner(input).useDelimiter("\\s*fish\\s*");
* System.out.println(s.nextInt());
* System.out.println(s.nextInt());
* System.out.println(s.next());
* System.out.println(s.next());
* s.close();
* }* prints the following output: *
{@code
* 1
* 2
* red
* blue
* }The same output can be generated with this code, which uses a regular * expression to parse all four tokens at once: *
{@code
* String input = "1 fish 2 fish red fish blue fish";
* Scanner s = new Scanner(input);
* s.findInLine("(\\d+) fish (\\d+) fish (\\w+) fish (\\w+)");
* MatchResult result = s.match();
* for (int i=1; i<=result.groupCount(); i++)
* System.out.println(result.group(i));
* s.close();
* }The default whitespace delimiter used * by a scanner is as recognized by {@link java.lang.Character}.{@link * java.lang.Character#isWhitespace(char) isWhitespace}. The {@link #reset} * method will reset the value of the scanner's delimiter to the default * whitespace delimiter regardless of whether it was previously changed. * *
A scanning operation may block waiting for input. * *
The {@link #next} and {@link #hasNext} methods and their * primitive-type companion methods (such as {@link #nextInt} and * {@link #hasNextInt}) first skip any input that matches the delimiter * pattern, and then attempt to return the next token. Both hasNext * and next methods may block waiting for further input. Whether a * hasNext method blocks has no connection to whether or not its * associated next method will block. * *
The {@link #findInLine}, {@link #findWithinHorizon}, and {@link #skip} * methods operate independently of the delimiter pattern. These methods will * attempt to match the specified pattern with no regard to delimiters in the * input and thus can be used in special circumstances where delimiters are * not relevant. These methods may block waiting for more input. * *
When a scanner throws an {@link InputMismatchException}, the scanner * will not pass the token that caused the exception, so that it may be * retrieved or skipped via some other method. * *
Depending upon the type of delimiting pattern, empty tokens may be * returned. For example, the pattern "\\s+" will return no empty * tokens since it matches multiple instances of the delimiter. The delimiting * pattern "\\s" could return empty tokens since it only passes one * space at a time. * *
A scanner can read text from any object which implements the {@link * java.lang.Readable} interface. If an invocation of the underlying * readable's {@link java.lang.Readable#read} method throws an {@link * java.io.IOException} then the scanner assumes that the end of the input * has been reached. The most recent IOException thrown by the * underlying readable can be retrieved via the {@link #ioException} method. * *
When a Scanner is closed, it will close its input source
* if the source implements the {@link java.io.Closeable} interface.
*
*
A Scanner is not safe for multithreaded use without
* external synchronization.
*
*
Unless otherwise mentioned, passing a null parameter into
* any method of a Scanner will cause a
* NullPointerException to be thrown.
*
*
A scanner will default to interpreting numbers as decimal unless a
* different radix has been set by using the {@link #useRadix} method. The
* {@link #reset} method will reset the value of the scanner's radix to
* 10 regardless of whether it was previously changed.
*
*
An instance of this class is capable of scanning numbers in the standard * formats as well as in the formats of the scanner's locale. A scanner's * initial locale is the value returned by the {@link * java.util.Locale#getDefault(Locale.Category) * Locale.getDefault(Locale.Category.FORMAT)} method; it may be changed via the {@link * #useLocale} method. The {@link #reset} method will reset the value of the * scanner's locale to the initial locale regardless of whether it was * previously changed. * *
The localized formats are defined in terms of the following parameters, * which for a particular locale are taken from that locale's {@link * java.text.DecimalFormat DecimalFormat} object, df, and its and * {@link java.text.DecimalFormatSymbols DecimalFormatSymbols} object, * dfs. * *
* **
- LocalGroupSeparator *
- The character used to separate thousands groups, * i.e., dfs.{@link * java.text.DecimalFormatSymbols#getGroupingSeparator * getGroupingSeparator()} *
- LocalDecimalSeparator *
- The character used for the decimal point, * i.e., dfs.{@link * java.text.DecimalFormatSymbols#getDecimalSeparator * getDecimalSeparator()} *
- LocalPositivePrefix *
- The string that appears before a positive number (may * be empty), i.e., df.{@link * java.text.DecimalFormat#getPositivePrefix * getPositivePrefix()} *
- LocalPositiveSuffix *
- The string that appears after a positive number (may be * empty), i.e., df.{@link * java.text.DecimalFormat#getPositiveSuffix * getPositiveSuffix()} *
- LocalNegativePrefix *
- The string that appears before a negative number (may * be empty), i.e., df.{@link * java.text.DecimalFormat#getNegativePrefix * getNegativePrefix()} *
- LocalNegativeSuffix *
- The string that appears after a negative number (may be * empty), i.e., df.{@link * java.text.DecimalFormat#getNegativeSuffix * getNegativeSuffix()} *
- LocalNaN *
- The string that represents not-a-number for * floating-point values, * i.e., dfs.{@link * java.text.DecimalFormatSymbols#getNaN * getNaN()} *
- LocalInfinity *
- The string that represents infinity for floating-point * values, i.e., dfs.{@link * java.text.DecimalFormatSymbols#getInfinity * getInfinity()} *
The strings that can be parsed as numbers by an instance of this class * are specified in terms of the following regular-expression grammar, where * Rmax is the highest digit in the radix being used (for example, Rmax is 9 in base 10). * *
Whitespace is not significant in the above regular expressions.
*
* @since 1.5
*/
public final class Scanner implements Iterator If this scanner has not yet been closed then if its underlying
* {@linkplain java.lang.Readable readable} also implements the {@link
* java.io.Closeable} interface then the readable's close method
* will be invoked. If this scanner is already closed then invoking this
* method will have no effect.
*
* Attempting to perform search operations after a scanner has
* been closed will result in an {@link IllegalStateException}.
*
*/
public void close() {
if (closed)
return;
if (source instanceof Closeable) {
try {
((Closeable)source).close();
} catch (IOException ioe) {
lastException = ioe;
}
}
sourceClosed = true;
source = null;
closed = true;
}
/**
* Returns the An invocation of this method of the form
* useDelimiter(pattern) behaves in exactly the same way as the
* invocation useDelimiter(Pattern.compile(pattern)).
*
* Invoking the {@link #reset} method will set the scanner's delimiter
* to the default.
*
* @param pattern A string specifying a delimiting pattern
* @return this scanner
*/
public Scanner useDelimiter(String pattern) {
delimPattern = patternCache.forName(pattern);
return this;
}
/**
* Returns this scanner's locale.
*
* A scanner's locale affects many elements of its default
* primitive matching regular expressions; see
* localized numbers above.
*
* @return this scanner's locale
*/
public Locale locale() {
return this.locale;
}
/**
* Sets this scanner's locale to the specified locale.
*
* A scanner's locale affects many elements of its default
* primitive matching regular expressions; see
* localized numbers above.
*
* Invoking the {@link #reset} method will set the scanner's locale to
* the initial locale.
*
* @param locale A string specifying the locale to use
* @return this scanner
*/
public Scanner useLocale(Locale locale) {
if (locale.equals(this.locale))
return this;
this.locale = locale;
DecimalFormat df =
(DecimalFormat)NumberFormat.getNumberInstance(locale);
DecimalFormatSymbols dfs = DecimalFormatSymbols.getInstance(locale);
// These must be literalized to avoid collision with regex
// metacharacters such as dot or parenthesis
groupSeparator = "\\" + dfs.getGroupingSeparator();
decimalSeparator = "\\" + dfs.getDecimalSeparator();
// Quoting the nonzero length locale-specific things
// to avoid potential conflict with metacharacters
nanString = "\\Q" + dfs.getNaN() + "\\E";
infinityString = "\\Q" + dfs.getInfinity() + "\\E";
positivePrefix = df.getPositivePrefix();
if (positivePrefix.length() > 0)
positivePrefix = "\\Q" + positivePrefix + "\\E";
negativePrefix = df.getNegativePrefix();
if (negativePrefix.length() > 0)
negativePrefix = "\\Q" + negativePrefix + "\\E";
positiveSuffix = df.getPositiveSuffix();
if (positiveSuffix.length() > 0)
positiveSuffix = "\\Q" + positiveSuffix + "\\E";
negativeSuffix = df.getNegativeSuffix();
if (negativeSuffix.length() > 0)
negativeSuffix = "\\Q" + negativeSuffix + "\\E";
// Force rebuilding and recompilation of locale dependent
// primitive patterns
integerPattern = null;
floatPattern = null;
return this;
}
/**
* Returns this scanner's default radix.
*
* A scanner's radix affects elements of its default
* number matching regular expressions; see
* localized numbers above.
*
* @return the default radix of this scanner
*/
public int radix() {
return this.defaultRadix;
}
/**
* Sets this scanner's default radix to the specified radix.
*
* A scanner's radix affects elements of its default
* number matching regular expressions; see
* localized numbers above.
*
* If the radix is less than Invoking the {@link #reset} method will set the scanner's radix to
* The various Returns the string representation of this An invocation of this method of the form hasNext(pattern)
* behaves in exactly the same way as the invocation
* hasNext(Pattern.compile(pattern)).
*
* @param pattern a string specifying the pattern to scan
* @return true if and only if this scanner has another token matching
* the specified pattern
* @throws IllegalStateException if this scanner is closed
*/
public boolean hasNext(String pattern) {
return hasNext(patternCache.forName(pattern));
}
/**
* Returns the next token if it matches the pattern constructed from the
* specified string. If the match is successful, the scanner advances
* past the input that matched the pattern.
*
* An invocation of this method of the form next(pattern)
* behaves in exactly the same way as the invocation
* next(Pattern.compile(pattern)).
*
* @param pattern a string specifying the pattern to scan
* @return the next token
* @throws NoSuchElementException if no such tokens are available
* @throws IllegalStateException if this scanner is closed
*/
public String next(String pattern) {
return next(patternCache.forName(pattern));
}
/**
* Returns true if the next complete token matches the specified pattern.
* A complete token is prefixed and postfixed by input that matches
* the delimiter pattern. This method may block while waiting for input.
* The scanner does not advance past any input.
*
* @param pattern the pattern to scan for
* @return true if and only if this scanner has another token matching
* the specified pattern
* @throws IllegalStateException if this scanner is closed
*/
public boolean hasNext(Pattern pattern) {
ensureOpen();
if (pattern == null)
throw new NullPointerException();
hasNextPattern = null;
saveState();
while (true) {
if (getCompleteTokenInBuffer(pattern) != null) {
matchValid = true;
cacheResult();
return revertState(true);
}
if (needInput)
readInput();
else
return revertState(false);
}
}
/**
* Returns the next token if it matches the specified pattern. This
* method may block while waiting for input to scan, even if a previous
* invocation of {@link #hasNext(Pattern)} returned Since this method continues to search through the input looking
* for a line separator, it may buffer all of the input searching for
* the line to skip if no line separators are present.
*
* @return the line that was skipped
* @throws NoSuchElementException if no line was found
* @throws IllegalStateException if this scanner is closed
*/
public String nextLine() {
if (hasNextPattern == linePattern())
return getCachedResult();
clearCaches();
String result = findWithinHorizon(linePattern, 0);
if (result == null)
throw new NoSuchElementException("No line found");
MatchResult mr = this.match();
String lineSep = mr.group(1);
if (lineSep != null)
result = result.substring(0, result.length() - lineSep.length());
if (result == null)
throw new NoSuchElementException();
else
return result;
}
// Public methods that ignore delimiters
/**
* Attempts to find the next occurrence of a pattern constructed from the
* specified string, ignoring delimiters.
*
* An invocation of this method of the form findInLine(pattern)
* behaves in exactly the same way as the invocation
* findInLine(Pattern.compile(pattern)).
*
* @param pattern a string specifying the pattern to search for
* @return the text that matched the specified pattern
* @throws IllegalStateException if this scanner is closed
*/
public String findInLine(String pattern) {
return findInLine(patternCache.forName(pattern));
}
/**
* Attempts to find the next occurrence of the specified pattern ignoring
* delimiters. If the pattern is found before the next line separator, the
* scanner advances past the input that matched and returns the string that
* matched the pattern.
* If no such pattern is detected in the input up to the next line
* separator, then Since this method continues to search through the input looking
* for the specified pattern, it may buffer all of the input searching for
* the desired token if no line separators are present.
*
* @param pattern the pattern to scan for
* @return the text that matched the specified pattern
* @throws IllegalStateException if this scanner is closed
*/
public String findInLine(Pattern pattern) {
ensureOpen();
if (pattern == null)
throw new NullPointerException();
clearCaches();
// Expand buffer to include the next newline or end of input
int endPosition = 0;
saveState();
while (true) {
String token = findPatternInBuffer(separatorPattern(), 0);
if (token != null) {
endPosition = matcher.start();
break; // up to next newline
}
if (needInput) {
readInput();
} else {
endPosition = buf.limit();
break; // up to end of input
}
}
revertState();
int horizonForLine = endPosition - position;
// If there is nothing between the current pos and the next
// newline simply return null, invoking findWithinHorizon
// with "horizon=0" will scan beyond the line bound.
if (horizonForLine == 0)
return null;
// Search for the pattern
return findWithinHorizon(pattern, horizonForLine);
}
/**
* Attempts to find the next occurrence of a pattern constructed from the
* specified string, ignoring delimiters.
*
* An invocation of this method of the form
* findWithinHorizon(pattern) behaves in exactly the same way as
* the invocation
* findWithinHorizon(Pattern.compile(pattern, horizon)).
*
* @param pattern a string specifying the pattern to search for
* @param horizon the search horizon
* @return the text that matched the specified pattern
* @throws IllegalStateException if this scanner is closed
* @throws IllegalArgumentException if horizon is negative
*/
public String findWithinHorizon(String pattern, int horizon) {
return findWithinHorizon(patternCache.forName(pattern), horizon);
}
/**
* Attempts to find the next occurrence of the specified pattern.
*
* This method searches through the input up to the specified
* search horizon, ignoring delimiters. If the pattern is found the
* scanner advances past the input that matched and returns the string
* that matched the pattern. If no such pattern is detected then the
* null is returned and the scanner's position remains unchanged. This
* method may block waiting for input that matches the pattern.
*
* A scanner will never search more than If horizon is If horizon is negative, then an IllegalArgumentException is
* thrown.
*
* @param pattern the pattern to scan for
* @param horizon the search horizon
* @return the text that matched the specified pattern
* @throws IllegalStateException if this scanner is closed
* @throws IllegalArgumentException if horizon is negative
*/
public String findWithinHorizon(Pattern pattern, int horizon) {
ensureOpen();
if (pattern == null)
throw new NullPointerException();
if (horizon < 0)
throw new IllegalArgumentException("horizon < 0");
clearCaches();
// Search for the pattern
while (true) {
String token = findPatternInBuffer(pattern, horizon);
if (token != null) {
matchValid = true;
return token;
}
if (needInput)
readInput();
else
break; // up to end of input
}
return null;
}
/**
* Skips input that matches the specified pattern, ignoring delimiters.
* This method will skip input if an anchored match of the specified
* pattern succeeds.
*
* If a match to the specified pattern is not found at the
* current position, then no input is skipped and a
* NoSuchElementException is thrown.
*
* Since this method seeks to match the specified pattern starting at
* the scanner's current position, patterns that can match a lot of
* input (".*", for example) may cause the scanner to buffer a large
* amount of input.
*
* Note that it is possible to skip something without risking a
* An invocation of this method of the form skip(pattern)
* behaves in exactly the same way as the invocation
* skip(Pattern.compile(pattern)).
*
* @param pattern a string specifying the pattern to skip over
* @return this scanner
* @throws IllegalStateException if this scanner is closed
*/
public Scanner skip(String pattern) {
return skip(patternCache.forName(pattern));
}
// Convenience methods for scanning primitives
/**
* Returns true if the next token in this scanner's input can be
* interpreted as a boolean value using a case insensitive pattern
* created from the string "true|false". The scanner does not
* advance past the input that matched.
*
* @return true if and only if this scanner's next token is a valid
* boolean value
* @throws IllegalStateException if this scanner is closed
*/
public boolean hasNextBoolean() {
return hasNext(boolPattern());
}
/**
* Scans the next token of the input into a boolean value and returns
* that value. This method will throw An invocation of this method of the form
* nextByte() behaves in exactly the same way as the
* invocation nextByte(radix), where If the next token matches the Integer regular expression defined
* above then the token is converted into a byte value as if by
* removing all locale specific prefixes, group separators, and locale
* specific suffixes, then mapping non-ASCII digits into ASCII
* digits via {@link Character#digit Character.digit}, prepending a
* negative sign (-) if the locale specific negative prefixes and suffixes
* were present, and passing the resulting string to
* {@link Byte#parseByte(String, int) Byte.parseByte} with the
* specified radix.
*
* @param radix the radix used to interpret the token as a byte value
* @return the byte scanned from the input
* @throws InputMismatchException
* if the next token does not match the Integer
* regular expression, or is out of range
* @throws NoSuchElementException if input is exhausted
* @throws IllegalStateException if this scanner is closed
*/
public byte nextByte(int radix) {
// Check cached result
if ((typeCache != null) && (typeCache instanceof Byte)
&& this.radix == radix) {
byte val = ((Byte)typeCache).byteValue();
useTypeCache();
return val;
}
setRadix(radix);
clearCaches();
// Search for next byte
try {
String s = next(integerPattern());
if (matcher.group(SIMPLE_GROUP_INDEX) == null)
s = processIntegerToken(s);
return Byte.parseByte(s, radix);
} catch (NumberFormatException nfe) {
position = matcher.start(); // don't skip bad token
throw new InputMismatchException(nfe.getMessage());
}
}
/**
* Returns true if the next token in this scanner's input can be
* interpreted as a short value in the default radix using the
* {@link #nextShort} method. The scanner does not advance past any input.
*
* @return true if and only if this scanner's next token is a valid
* short value in the default radix
* @throws IllegalStateException if this scanner is closed
*/
public boolean hasNextShort() {
return hasNextShort(defaultRadix);
}
/**
* Returns true if the next token in this scanner's input can be
* interpreted as a short value in the specified radix using the
* {@link #nextShort} method. The scanner does not advance past any input.
*
* @param radix the radix used to interpret the token as a short value
* @return true if and only if this scanner's next token is a valid
* short value in the specified radix
* @throws IllegalStateException if this scanner is closed
*/
public boolean hasNextShort(int radix) {
setRadix(radix);
boolean result = hasNext(integerPattern());
if (result) { // Cache it
try {
String s = (matcher.group(SIMPLE_GROUP_INDEX) == null) ?
processIntegerToken(hasNextResult) :
hasNextResult;
typeCache = Short.parseShort(s, radix);
} catch (NumberFormatException nfe) {
result = false;
}
}
return result;
}
/**
* Scans the next token of the input as a short.
*
* An invocation of this method of the form
* nextShort() behaves in exactly the same way as the
* invocation nextShort(radix), where If the next token matches the Integer regular expression defined
* above then the token is converted into a short value as if by
* removing all locale specific prefixes, group separators, and locale
* specific suffixes, then mapping non-ASCII digits into ASCII
* digits via {@link Character#digit Character.digit}, prepending a
* negative sign (-) if the locale specific negative prefixes and suffixes
* were present, and passing the resulting string to
* {@link Short#parseShort(String, int) Short.parseShort} with the
* specified radix.
*
* @param radix the radix used to interpret the token as a short value
* @return the short scanned from the input
* @throws InputMismatchException
* if the next token does not match the Integer
* regular expression, or is out of range
* @throws NoSuchElementException if input is exhausted
* @throws IllegalStateException if this scanner is closed
*/
public short nextShort(int radix) {
// Check cached result
if ((typeCache != null) && (typeCache instanceof Short)
&& this.radix == radix) {
short val = ((Short)typeCache).shortValue();
useTypeCache();
return val;
}
setRadix(radix);
clearCaches();
// Search for next short
try {
String s = next(integerPattern());
if (matcher.group(SIMPLE_GROUP_INDEX) == null)
s = processIntegerToken(s);
return Short.parseShort(s, radix);
} catch (NumberFormatException nfe) {
position = matcher.start(); // don't skip bad token
throw new InputMismatchException(nfe.getMessage());
}
}
/**
* Returns true if the next token in this scanner's input can be
* interpreted as an int value in the default radix using the
* {@link #nextInt} method. The scanner does not advance past any input.
*
* @return true if and only if this scanner's next token is a valid
* int value
* @throws IllegalStateException if this scanner is closed
*/
public boolean hasNextInt() {
return hasNextInt(defaultRadix);
}
/**
* Returns true if the next token in this scanner's input can be
* interpreted as an int value in the specified radix using the
* {@link #nextInt} method. The scanner does not advance past any input.
*
* @param radix the radix used to interpret the token as an int value
* @return true if and only if this scanner's next token is a valid
* int value
* @throws IllegalStateException if this scanner is closed
*/
public boolean hasNextInt(int radix) {
setRadix(radix);
boolean result = hasNext(integerPattern());
if (result) { // Cache it
try {
String s = (matcher.group(SIMPLE_GROUP_INDEX) == null) ?
processIntegerToken(hasNextResult) :
hasNextResult;
typeCache = Integer.parseInt(s, radix);
} catch (NumberFormatException nfe) {
result = false;
}
}
return result;
}
/**
* The integer token must be stripped of prefixes, group separators,
* and suffixes, non ascii digits must be converted into ascii digits
* before parse will accept it.
*/
private String processIntegerToken(String token) {
String result = token.replaceAll(""+groupSeparator, "");
boolean isNegative = false;
int preLen = negativePrefix.length();
if ((preLen > 0) && result.startsWith(negativePrefix)) {
isNegative = true;
result = result.substring(preLen);
}
int sufLen = negativeSuffix.length();
if ((sufLen > 0) && result.endsWith(negativeSuffix)) {
isNegative = true;
result = result.substring(result.length() - sufLen,
result.length());
}
if (isNegative)
result = "-" + result;
return result;
}
/**
* Scans the next token of the input as an int.
*
* An invocation of this method of the form
* nextInt() behaves in exactly the same way as the
* invocation nextInt(radix), where If the next token matches the Integer regular expression defined
* above then the token is converted into an int value as if by
* removing all locale specific prefixes, group separators, and locale
* specific suffixes, then mapping non-ASCII digits into ASCII
* digits via {@link Character#digit Character.digit}, prepending a
* negative sign (-) if the locale specific negative prefixes and suffixes
* were present, and passing the resulting string to
* {@link Integer#parseInt(String, int) Integer.parseInt} with the
* specified radix.
*
* @param radix the radix used to interpret the token as an int value
* @return the int scanned from the input
* @throws InputMismatchException
* if the next token does not match the Integer
* regular expression, or is out of range
* @throws NoSuchElementException if input is exhausted
* @throws IllegalStateException if this scanner is closed
*/
public int nextInt(int radix) {
// Check cached result
if ((typeCache != null) && (typeCache instanceof Integer)
&& this.radix == radix) {
int val = ((Integer)typeCache).intValue();
useTypeCache();
return val;
}
setRadix(radix);
clearCaches();
// Search for next int
try {
String s = next(integerPattern());
if (matcher.group(SIMPLE_GROUP_INDEX) == null)
s = processIntegerToken(s);
return Integer.parseInt(s, radix);
} catch (NumberFormatException nfe) {
position = matcher.start(); // don't skip bad token
throw new InputMismatchException(nfe.getMessage());
}
}
/**
* Returns true if the next token in this scanner's input can be
* interpreted as a long value in the default radix using the
* {@link #nextLong} method. The scanner does not advance past any input.
*
* @return true if and only if this scanner's next token is a valid
* long value
* @throws IllegalStateException if this scanner is closed
*/
public boolean hasNextLong() {
return hasNextLong(defaultRadix);
}
/**
* Returns true if the next token in this scanner's input can be
* interpreted as a long value in the specified radix using the
* {@link #nextLong} method. The scanner does not advance past any input.
*
* @param radix the radix used to interpret the token as a long value
* @return true if and only if this scanner's next token is a valid
* long value
* @throws IllegalStateException if this scanner is closed
*/
public boolean hasNextLong(int radix) {
setRadix(radix);
boolean result = hasNext(integerPattern());
if (result) { // Cache it
try {
String s = (matcher.group(SIMPLE_GROUP_INDEX) == null) ?
processIntegerToken(hasNextResult) :
hasNextResult;
typeCache = Long.parseLong(s, radix);
} catch (NumberFormatException nfe) {
result = false;
}
}
return result;
}
/**
* Scans the next token of the input as a long.
*
* An invocation of this method of the form
* nextLong() behaves in exactly the same way as the
* invocation nextLong(radix), where If the next token matches the Integer regular expression defined
* above then the token is converted into a long value as if by
* removing all locale specific prefixes, group separators, and locale
* specific suffixes, then mapping non-ASCII digits into ASCII
* digits via {@link Character#digit Character.digit}, prepending a
* negative sign (-) if the locale specific negative prefixes and suffixes
* were present, and passing the resulting string to
* {@link Long#parseLong(String, int) Long.parseLong} with the
* specified radix.
*
* @param radix the radix used to interpret the token as an int value
* @return the long scanned from the input
* @throws InputMismatchException
* if the next token does not match the Integer
* regular expression, or is out of range
* @throws NoSuchElementException if input is exhausted
* @throws IllegalStateException if this scanner is closed
*/
public long nextLong(int radix) {
// Check cached result
if ((typeCache != null) && (typeCache instanceof Long)
&& this.radix == radix) {
long val = ((Long)typeCache).longValue();
useTypeCache();
return val;
}
setRadix(radix);
clearCaches();
try {
String s = next(integerPattern());
if (matcher.group(SIMPLE_GROUP_INDEX) == null)
s = processIntegerToken(s);
return Long.parseLong(s, radix);
} catch (NumberFormatException nfe) {
position = matcher.start(); // don't skip bad token
throw new InputMismatchException(nfe.getMessage());
}
}
/**
* The float token must be stripped of prefixes, group separators,
* and suffixes, non ascii digits must be converted into ascii digits
* before parseFloat will accept it.
*
* If there are non-ascii digits in the token these digits must
* be processed before the token is passed to parseFloat.
*/
private String processFloatToken(String token) {
String result = token.replaceAll(groupSeparator, "");
if (!decimalSeparator.equals("\\."))
result = result.replaceAll(decimalSeparator, ".");
boolean isNegative = false;
int preLen = negativePrefix.length();
if ((preLen > 0) && result.startsWith(negativePrefix)) {
isNegative = true;
result = result.substring(preLen);
}
int sufLen = negativeSuffix.length();
if ((sufLen > 0) && result.endsWith(negativeSuffix)) {
isNegative = true;
result = result.substring(result.length() - sufLen,
result.length());
}
if (result.equals(nanString))
result = "NaN";
if (result.equals(infinityString))
result = "Infinity";
if (isNegative)
result = "-" + result;
// Translate non-ASCII digits
Matcher m = NON_ASCII_DIGIT.matcher(result);
if (m.find()) {
StringBuilder inASCII = new StringBuilder();
for (int i=0; i If the next token matches the Float regular expression defined above
* then the token is converted into a float value as if by
* removing all locale specific prefixes, group separators, and locale
* specific suffixes, then mapping non-ASCII digits into ASCII
* digits via {@link Character#digit Character.digit}, prepending a
* negative sign (-) if the locale specific negative prefixes and suffixes
* were present, and passing the resulting string to
* {@link Float#parseFloat Float.parseFloat}. If the token matches
* the localized NaN or infinity strings, then either "Nan" or "Infinity"
* is passed to {@link Float#parseFloat(String) Float.parseFloat} as
* appropriate.
*
* @return the float scanned from the input
* @throws InputMismatchException
* if the next token does not match the Float
* regular expression, or is out of range
* @throws NoSuchElementException if input is exhausted
* @throws IllegalStateException if this scanner is closed
*/
public float nextFloat() {
// Check cached result
if ((typeCache != null) && (typeCache instanceof Float)) {
float val = ((Float)typeCache).floatValue();
useTypeCache();
return val;
}
setRadix(10);
clearCaches();
try {
return Float.parseFloat(processFloatToken(next(floatPattern())));
} catch (NumberFormatException nfe) {
position = matcher.start(); // don't skip bad token
throw new InputMismatchException(nfe.getMessage());
}
}
/**
* Returns true if the next token in this scanner's input can be
* interpreted as a double value using the {@link #nextDouble}
* method. The scanner does not advance past any input.
*
* @return true if and only if this scanner's next token is a valid
* double value
* @throws IllegalStateException if this scanner is closed
*/
public boolean hasNextDouble() {
setRadix(10);
boolean result = hasNext(floatPattern());
if (result) { // Cache it
try {
String s = processFloatToken(hasNextResult);
typeCache = Double.valueOf(Double.parseDouble(s));
} catch (NumberFormatException nfe) {
result = false;
}
}
return result;
}
/**
* Scans the next token of the input as a double.
* This method will throw If the next token matches the Float regular expression defined above
* then the token is converted into a double value as if by
* removing all locale specific prefixes, group separators, and locale
* specific suffixes, then mapping non-ASCII digits into ASCII
* digits via {@link Character#digit Character.digit}, prepending a
* negative sign (-) if the locale specific negative prefixes and suffixes
* were present, and passing the resulting string to
* {@link Double#parseDouble Double.parseDouble}. If the token matches
* the localized NaN or infinity strings, then either "Nan" or "Infinity"
* is passed to {@link Double#parseDouble(String) Double.parseDouble} as
* appropriate.
*
* @return the double scanned from the input
* @throws InputMismatchException
* if the next token does not match the Float
* regular expression, or is out of range
* @throws NoSuchElementException if the input is exhausted
* @throws IllegalStateException if this scanner is closed
*/
public double nextDouble() {
// Check cached result
if ((typeCache != null) && (typeCache instanceof Double)) {
double val = ((Double)typeCache).doubleValue();
useTypeCache();
return val;
}
setRadix(10);
clearCaches();
// Search for next float
try {
return Double.parseDouble(processFloatToken(next(floatPattern())));
} catch (NumberFormatException nfe) {
position = matcher.start(); // don't skip bad token
throw new InputMismatchException(nfe.getMessage());
}
}
// Convenience methods for scanning multi precision numbers
/**
* Returns true if the next token in this scanner's input can be
* interpreted as a An invocation of this method of the form
* nextBigInteger() behaves in exactly the same way as the
* invocation nextBigInteger(radix), where If the next token matches the Integer regular expression defined
* above then the token is converted into a BigInteger value as if
* by removing all group separators, mapping non-ASCII digits into ASCII
* digits via the {@link Character#digit Character.digit}, and passing the
* resulting string to the {@link
* java.math.BigInteger#BigInteger(java.lang.String)
* BigInteger(String, int)} constructor with the specified radix.
*
* @param radix the radix used to interpret the token
* @return the BigInteger scanned from the input
* @throws InputMismatchException
* if the next token does not match the Integer
* regular expression, or is out of range
* @throws NoSuchElementException if the input is exhausted
* @throws IllegalStateException if this scanner is closed
*/
public BigInteger nextBigInteger(int radix) {
// Check cached result
if ((typeCache != null) && (typeCache instanceof BigInteger)
&& this.radix == radix) {
BigInteger val = (BigInteger)typeCache;
useTypeCache();
return val;
}
setRadix(radix);
clearCaches();
// Search for next int
try {
String s = next(integerPattern());
if (matcher.group(SIMPLE_GROUP_INDEX) == null)
s = processIntegerToken(s);
return new BigInteger(s, radix);
} catch (NumberFormatException nfe) {
position = matcher.start(); // don't skip bad token
throw new InputMismatchException(nfe.getMessage());
}
}
/**
* Returns true if the next token in this scanner's input can be
* interpreted as a If the next token matches the Decimal regular expression defined
* above then the token is converted into a BigDecimal value as if
* by removing all group separators, mapping non-ASCII digits into ASCII
* digits via the {@link Character#digit Character.digit}, and passing the
* resulting string to the {@link
* java.math.BigDecimal#BigDecimal(java.lang.String) BigDecimal(String)}
* constructor.
*
* @return the BigDecimal scanned from the input
* @throws InputMismatchException
* if the next token does not match the Decimal
* regular expression, or is out of range
* @throws NoSuchElementException if the input is exhausted
* @throws IllegalStateException if this scanner is closed
*/
public BigDecimal nextBigDecimal() {
// Check cached result
if ((typeCache != null) && (typeCache instanceof BigDecimal)) {
BigDecimal val = (BigDecimal)typeCache;
useTypeCache();
return val;
}
setRadix(10);
clearCaches();
// Search for next float
try {
String s = processFloatToken(next(decimalPattern()));
return new BigDecimal(s);
} catch (NumberFormatException nfe) {
position = matcher.start(); // don't skip bad token
throw new InputMismatchException(nfe.getMessage());
}
}
/**
* Resets this scanner.
*
* Resetting a scanner discards all of its explicit state
* information which may have been changed by invocations of {@link
* #useDelimiter}, {@link #useLocale}, or {@link #useRadix}.
*
* An invocation of this method of the form
* scanner.reset() behaves in exactly the same way as the
* invocation
*
* Scanner that returns values scanned
* from the specified source delimited by the specified pattern.
*
* @param source A character source implementing the Readable interface
* @param pattern A delimiting pattern
*/
private Scanner(Readable source, Pattern pattern) {
assert source != null : "source should not be null";
assert pattern != null : "pattern should not be null";
this.source = source;
delimPattern = pattern;
buf = CharBuffer.allocate(BUFFER_SIZE);
buf.limit(0);
matcher = delimPattern.matcher(buf);
matcher.useTransparentBounds(true);
matcher.useAnchoringBounds(false);
useLocale(Locale.getDefault(Locale.Category.FORMAT));
}
/**
* Constructs a new Scanner that produces values scanned
* from the specified source.
*
* @param source A character source implementing the {@link Readable}
* interface
*/
public Scanner(Readable source) {
this(Objects.requireNonNull(source, "source"), WHITESPACE_PATTERN);
}
/**
* Constructs a new Scanner that produces values scanned
* from the specified input stream. Bytes from the stream are converted
* into characters using the underlying platform's
* {@linkplain java.nio.charset.Charset#defaultCharset() default charset}.
*
* @param source An input stream to be scanned
*/
public Scanner(InputStream source) {
this(new InputStreamReader(source), WHITESPACE_PATTERN);
}
/**
* Constructs a new Scanner that produces values scanned
* from the specified input stream. Bytes from the stream are converted
* into characters using the specified charset.
*
* @param source An input stream to be scanned
* @param charsetName The encoding type used to convert bytes from the
* stream into characters to be scanned
* @throws IllegalArgumentException if the specified character set
* does not exist
*/
public Scanner(InputStream source, String charsetName) {
this(makeReadable(Objects.requireNonNull(source, "source"), toCharset(charsetName)),
WHITESPACE_PATTERN);
}
/**
* Returns a charset object for the given charset name.
* @throws NullPointerException is csn is null
* @throws IllegalArgumentException if the charset is not supported
*/
private static Charset toCharset(String csn) {
Objects.requireNonNull(csn, "charsetName");
try {
return Charset.forName(csn);
} catch (IllegalCharsetNameException|UnsupportedCharsetException e) {
// IllegalArgumentException should be thrown
throw new IllegalArgumentException(e);
}
}
private static Readable makeReadable(InputStream source, Charset charset) {
return new InputStreamReader(source, charset);
}
/**
* Constructs a new Scanner that produces values scanned
* from the specified file. Bytes from the file are converted into
* characters using the underlying platform's
* {@linkplain java.nio.charset.Charset#defaultCharset() default charset}.
*
* @param source A file to be scanned
* @throws FileNotFoundException if source is not found
*/
public Scanner(File source) throws FileNotFoundException {
this((ReadableByteChannel)(new FileInputStream(source).getChannel()));
}
/**
* Constructs a new Scanner that produces values scanned
* from the specified file. Bytes from the file are converted into
* characters using the specified charset.
*
* @param source A file to be scanned
* @param charsetName The encoding type used to convert bytes from the file
* into characters to be scanned
* @throws FileNotFoundException if source is not found
* @throws IllegalArgumentException if the specified encoding is
* not found
*/
public Scanner(File source, String charsetName)
throws FileNotFoundException
{
this(Objects.requireNonNull(source), toDecoder(charsetName));
}
private Scanner(File source, CharsetDecoder dec)
throws FileNotFoundException
{
this(makeReadable((ReadableByteChannel)(new FileInputStream(source).getChannel()), dec));
}
private static CharsetDecoder toDecoder(String charsetName) {
Objects.requireNonNull(charsetName, "charsetName");
try {
return Charset.forName(charsetName).newDecoder();
} catch (IllegalCharsetNameException|UnsupportedCharsetException unused) {
throw new IllegalArgumentException(charsetName);
}
}
private static Readable makeReadable(ReadableByteChannel source,
CharsetDecoder dec) {
return Channels.newReader(source, dec, -1);
}
/**
* Constructs a new Scanner that produces values scanned
* from the specified file. Bytes from the file are converted into
* characters using the underlying platform's
* {@linkplain java.nio.charset.Charset#defaultCharset() default charset}.
*
* @param source
* the path to the file to be scanned
* @throws IOException
* if an I/O error occurs opening source
*
* @since 1.7
*/
public Scanner(Path source)
throws IOException
{
this(Files.newInputStream(source));
}
/**
* Constructs a new Scanner that produces values scanned
* from the specified file. Bytes from the file are converted into
* characters using the specified charset.
*
* @param source
* the path to the file to be scanned
* @param charsetName
* The encoding type used to convert bytes from the file
* into characters to be scanned
* @throws IOException
* if an I/O error occurs opening source
* @throws IllegalArgumentException
* if the specified encoding is not found
* @since 1.7
*/
public Scanner(Path source, String charsetName) throws IOException {
this(Objects.requireNonNull(source), toCharset(charsetName));
}
private Scanner(Path source, Charset charset) throws IOException {
this(makeReadable(Files.newInputStream(source), charset));
}
/**
* Constructs a new Scanner that produces values scanned
* from the specified string.
*
* @param source A string to scan
*/
public Scanner(String source) {
this(new StringReader(source), WHITESPACE_PATTERN);
}
/**
* Constructs a new Scanner that produces values scanned
* from the specified channel. Bytes from the source are converted into
* characters using the underlying platform's
* {@linkplain java.nio.charset.Charset#defaultCharset() default charset}.
*
* @param source A channel to scan
*/
public Scanner(ReadableByteChannel source) {
this(makeReadable(Objects.requireNonNull(source, "source")),
WHITESPACE_PATTERN);
}
private static Readable makeReadable(ReadableByteChannel source) {
return makeReadable(source, Charset.defaultCharset().newDecoder());
}
/**
* Constructs a new Scanner that produces values scanned
* from the specified channel. Bytes from the source are converted into
* characters using the specified charset.
*
* @param source A channel to scan
* @param charsetName The encoding type used to convert bytes from the
* channel into characters to be scanned
* @throws IllegalArgumentException if the specified character set
* does not exist
*/
public Scanner(ReadableByteChannel source, String charsetName) {
this(makeReadable(Objects.requireNonNull(source, "source"), toDecoder(charsetName)),
WHITESPACE_PATTERN);
}
// Private primitives used to support scanning
private void saveState() {
savedScannerPosition = position;
}
private void revertState() {
this.position = savedScannerPosition;
savedScannerPosition = -1;
skipped = false;
}
private boolean revertState(boolean b) {
this.position = savedScannerPosition;
savedScannerPosition = -1;
skipped = false;
return b;
}
private void cacheResult() {
hasNextResult = matcher.group();
hasNextPosition = matcher.end();
hasNextPattern = matcher.pattern();
}
private void cacheResult(String result) {
hasNextResult = result;
hasNextPosition = matcher.end();
hasNextPattern = matcher.pattern();
}
// Clears both regular cache and type cache
private void clearCaches() {
hasNextPattern = null;
typeCache = null;
}
// Also clears both the regular cache and the type cache
private String getCachedResult() {
position = hasNextPosition;
hasNextPattern = null;
typeCache = null;
return hasNextResult;
}
// Also clears both the regular cache and the type cache
private void useTypeCache() {
if (closed)
throw new IllegalStateException("Scanner closed");
position = hasNextPosition;
hasNextPattern = null;
typeCache = null;
}
// Tries to read more input. May block.
private void readInput() {
if (buf.limit() == buf.capacity())
makeSpace();
// Prepare to receive data
int p = buf.position();
buf.position(buf.limit());
buf.limit(buf.capacity());
int n = 0;
try {
n = source.read(buf);
} catch (IOException ioe) {
lastException = ioe;
n = -1;
}
if (n == -1) {
sourceClosed = true;
needInput = false;
}
if (n > 0)
needInput = false;
// Restore current position and limit for reading
buf.limit(buf.position());
buf.position(p);
}
// After this method is called there will either be an exception
// or else there will be space in the buffer
private boolean makeSpace() {
clearCaches();
int offset = savedScannerPosition == -1 ?
position : savedScannerPosition;
buf.position(offset);
// Gain space by compacting buffer
if (offset > 0) {
buf.compact();
translateSavedIndexes(offset);
position -= offset;
buf.flip();
return true;
}
// Gain space by growing buffer
int newSize = buf.capacity() * 2;
CharBuffer newBuf = CharBuffer.allocate(newSize);
newBuf.put(buf);
newBuf.flip();
translateSavedIndexes(offset);
position -= offset;
buf = newBuf;
matcher.reset(buf);
return true;
}
// When a buffer compaction/reallocation occurs the saved indexes must
// be modified appropriately
private void translateSavedIndexes(int offset) {
if (savedScannerPosition != -1)
savedScannerPosition -= offset;
}
// If we are at the end of input then NoSuchElement;
// If there is still input left then InputMismatch
private void throwFor() {
skipped = false;
if ((sourceClosed) && (position == buf.limit()))
throw new NoSuchElementException();
else
throw new InputMismatchException();
}
// Returns true if a complete token or partial token is in the buffer.
// It is not necessary to find a complete token since a partial token
// means that there will be another token with or without more input.
private boolean hasTokenInBuffer() {
matchValid = false;
matcher.usePattern(delimPattern);
matcher.region(position, buf.limit());
// Skip delims first
if (matcher.lookingAt())
position = matcher.end();
// If we are sitting at the end, no more tokens in buffer
if (position == buf.limit())
return false;
return true;
}
/*
* Returns a "complete token" that matches the specified pattern
*
* A token is complete if surrounded by delims; a partial token
* is prefixed by delims but not postfixed by them
*
* The position is advanced to the end of that complete token
*
* Pattern == null means accept any token at all
*
* Triple return:
* 1. valid string means it was found
* 2. null with needInput=false means we won't ever find it
* 3. null with needInput=true means try again after readInput
*/
private String getCompleteTokenInBuffer(Pattern pattern) {
matchValid = false;
// Skip delims first
matcher.usePattern(delimPattern);
if (!skipped) { // Enforcing only one skip of leading delims
matcher.region(position, buf.limit());
if (matcher.lookingAt()) {
// If more input could extend the delimiters then we must wait
// for more input
if (matcher.hitEnd() && !sourceClosed) {
needInput = true;
return null;
}
// The delims were whole and the matcher should skip them
skipped = true;
position = matcher.end();
}
}
// If we are sitting at the end, no more tokens in buffer
if (position == buf.limit()) {
if (sourceClosed)
return null;
needInput = true;
return null;
}
// Must look for next delims. Simply attempting to match the
// pattern at this point may find a match but it might not be
// the first longest match because of missing input, or it might
// match a partial token instead of the whole thing.
// Then look for next delims
matcher.region(position, buf.limit());
boolean foundNextDelim = matcher.find();
if (foundNextDelim && (matcher.end() == position)) {
// Zero length delimiter match; we should find the next one
// using the automatic advance past a zero length match;
// Otherwise we have just found the same one we just skipped
foundNextDelim = matcher.find();
}
if (foundNextDelim) {
// In the rare case that more input could cause the match
// to be lost and there is more input coming we must wait
// for more input. Note that hitting the end is okay as long
// as the match cannot go away. It is the beginning of the
// next delims we want to be sure about, we don't care if
// they potentially extend further.
if (matcher.requireEnd() && !sourceClosed) {
needInput = true;
return null;
}
int tokenEnd = matcher.start();
// There is a complete token.
if (pattern == null) {
// Must continue with match to provide valid MatchResult
pattern = FIND_ANY_PATTERN;
}
// Attempt to match against the desired pattern
matcher.usePattern(pattern);
matcher.region(position, tokenEnd);
if (matcher.matches()) {
String s = matcher.group();
position = matcher.end();
return s;
} else { // Complete token but it does not match
return null;
}
}
// If we can't find the next delims but no more input is coming,
// then we can treat the remainder as a whole token
if (sourceClosed) {
if (pattern == null) {
// Must continue with match to provide valid MatchResult
pattern = FIND_ANY_PATTERN;
}
// Last token; Match the pattern here or throw
matcher.usePattern(pattern);
matcher.region(position, buf.limit());
if (matcher.matches()) {
String s = matcher.group();
position = matcher.end();
return s;
}
// Last piece does not match
return null;
}
// There is a partial token in the buffer; must read more
// to complete it
needInput = true;
return null;
}
// Finds the specified pattern in the buffer up to horizon.
// Returns a match for the specified input pattern.
private String findPatternInBuffer(Pattern pattern, int horizon) {
matchValid = false;
matcher.usePattern(pattern);
int bufferLimit = buf.limit();
int horizonLimit = -1;
int searchLimit = bufferLimit;
if (horizon > 0) {
horizonLimit = position + horizon;
if (horizonLimit < bufferLimit)
searchLimit = horizonLimit;
}
matcher.region(position, searchLimit);
if (matcher.find()) {
if (matcher.hitEnd() && (!sourceClosed)) {
// The match may be longer if didn't hit horizon or real end
if (searchLimit != horizonLimit) {
// Hit an artificial end; try to extend the match
needInput = true;
return null;
}
// The match could go away depending on what is next
if ((searchLimit == horizonLimit) && matcher.requireEnd()) {
// Rare case: we hit the end of input and it happens
// that it is at the horizon and the end of input is
// required for the match.
needInput = true;
return null;
}
}
// Did not hit end, or hit real end, or hit horizon
position = matcher.end();
return matcher.group();
}
if (sourceClosed)
return null;
// If there is no specified horizon, or if we have not searched
// to the specified horizon yet, get more input
if ((horizon == 0) || (searchLimit != horizonLimit))
needInput = true;
return null;
}
// Returns a match for the specified input pattern anchored at
// the current position
private String matchPatternInBuffer(Pattern pattern) {
matchValid = false;
matcher.usePattern(pattern);
matcher.region(position, buf.limit());
if (matcher.lookingAt()) {
if (matcher.hitEnd() && (!sourceClosed)) {
// Get more input and try again
needInput = true;
return null;
}
position = matcher.end();
return matcher.group();
}
if (sourceClosed)
return null;
// Read more to find pattern
needInput = true;
return null;
}
// Throws if the scanner is closed
private void ensureOpen() {
if (closed)
throw new IllegalStateException("Scanner closed");
}
// Public methods
/**
* Closes this scanner.
*
* IOException last thrown by this
* Scanner's underlying Readable. This method
* returns null if no such exception exists.
*
* @return the last exception thrown by this scanner's readable
*/
public IOException ioException() {
return lastException;
}
/**
* Returns the Pattern this Scanner is currently
* using to match delimiters.
*
* @return this scanner's delimiting pattern.
*/
public Pattern delimiter() {
return delimPattern;
}
/**
* Sets this scanner's delimiting pattern to the specified pattern.
*
* @param pattern A delimiting pattern
* @return this scanner
*/
public Scanner useDelimiter(Pattern pattern) {
delimPattern = pattern;
return this;
}
/**
* Sets this scanner's delimiting pattern to a pattern constructed from
* the specified String.
*
* Character.MIN_RADIX
* or greater than Character.MAX_RADIX, then an
* IllegalArgumentException is thrown.
*
* 10.
*
* @param radix The radix to use when scanning numbers
* @return this scanner
* @throws IllegalArgumentException if radix is out of range
*/
public Scanner useRadix(int radix) {
if ((radix < Character.MIN_RADIX) || (radix > Character.MAX_RADIX))
throw new IllegalArgumentException("radix:"+radix);
if (this.defaultRadix == radix)
return this;
this.defaultRadix = radix;
// Force rebuilding and recompilation of radix dependent patterns
integerPattern = null;
return this;
}
// The next operation should occur in the specified radix but
// the default is left untouched.
private void setRadix(int radix) {
if (this.radix != radix) {
// Force rebuilding and recompilation of radix dependent patterns
integerPattern = null;
this.radix = radix;
}
}
/**
* Returns the match result of the last scanning operation performed
* by this scanner. This method throws IllegalStateException
* if no match has been performed, or if the last match was
* not successful.
*
* nextmethods of Scanner
* make a match result available if they complete without throwing an
* exception. For instance, after an invocation of the {@link #nextInt}
* method that returned an int, this method returns a
* MatchResult for the search of the
* Integer regular expression
* defined above. Similarly the {@link #findInLine},
* {@link #findWithinHorizon}, and {@link #skip} methods will make a
* match available if they succeed.
*
* @return a match result for the last match operation
* @throws IllegalStateException If no match result is available
*/
public MatchResult match() {
if (!matchValid)
throw new IllegalStateException("No match result available");
return matcher.toMatchResult();
}
/**
* Scanner. The
* string representation of a Scanner contains information
* that may be useful for debugging. The exact format is unspecified.
*
* @return The string representation of this scanner
*/
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("java.util.Scanner");
sb.append("[delimiters=").append(delimPattern).append(']');
sb.append("[position=").append(position).append(']');
sb.append("[match valid=").append(matchValid).append(']');
sb.append("[need input=").append(needInput).append(']');
sb.append("[source closed=").append(sourceClosed).append(']');
sb.append("[skipped=").append(skipped).append(']');
sb.append("[group separator=").append(groupSeparator).append(']');
sb.append("[decimal separator=").append(decimalSeparator).append(']');
sb.append("[positive prefix=").append(positivePrefix).append(']');
sb.append("[negative prefix=").append(negativePrefix).append(']');
sb.append("[positive suffix=").append(positiveSuffix).append(']');
sb.append("[negative suffix=").append(negativeSuffix).append(']');
sb.append("[NaN string=").append(nanString).append(']');
sb.append("[infinity string=").append(infinityString).append(']');
return sb.toString();
}
/**
* Returns true if this scanner has another token in its input.
* This method may block while waiting for input to scan.
* The scanner does not advance past any input.
*
* @return true if and only if this scanner has another token
* @throws IllegalStateException if this scanner is closed
* @see java.util.Iterator
*/
public boolean hasNext() {
ensureOpen();
saveState();
while (!sourceClosed) {
if (hasTokenInBuffer())
return revertState(true);
readInput();
}
boolean result = hasTokenInBuffer();
return revertState(result);
}
/**
* Finds and returns the next complete token from this scanner.
* A complete token is preceded and followed by input that matches
* the delimiter pattern. This method may block while waiting for input
* to scan, even if a previous invocation of {@link #hasNext} returned
* true.
*
* @return the next token
* @throws NoSuchElementException if no more tokens are available
* @throws IllegalStateException if this scanner is closed
* @see java.util.Iterator
*/
public String next() {
ensureOpen();
clearCaches();
while (true) {
String token = getCompleteTokenInBuffer(null);
if (token != null) {
matchValid = true;
skipped = false;
return token;
}
if (needInput)
readInput();
else
throwFor();
}
}
/**
* The remove operation is not supported by this implementation of
* Iterator.
*
* @throws UnsupportedOperationException if this method is invoked.
* @see java.util.Iterator
*/
public void remove() {
throw new UnsupportedOperationException();
}
/**
* Returns true if the next token matches the pattern constructed from the
* specified string. The scanner does not advance past any input.
*
* true.
* If the match is successful, the scanner advances past the input that
* matched the pattern.
*
* @param pattern the pattern to scan for
* @return the next token
* @throws NoSuchElementException if no more tokens are available
* @throws IllegalStateException if this scanner is closed
*/
public String next(Pattern pattern) {
ensureOpen();
if (pattern == null)
throw new NullPointerException();
// Did we already find this pattern?
if (hasNextPattern == pattern)
return getCachedResult();
clearCaches();
// Search for the pattern
while (true) {
String token = getCompleteTokenInBuffer(pattern);
if (token != null) {
matchValid = true;
skipped = false;
return token;
}
if (needInput)
readInput();
else
throwFor();
}
}
/**
* Returns true if there is another line in the input of this scanner.
* This method may block while waiting for input. The scanner does not
* advance past any input.
*
* @return true if and only if this scanner has another line of input
* @throws IllegalStateException if this scanner is closed
*/
public boolean hasNextLine() {
saveState();
String result = findWithinHorizon(linePattern(), 0);
if (result != null) {
MatchResult mr = this.match();
String lineSep = mr.group(1);
if (lineSep != null) {
result = result.substring(0, result.length() -
lineSep.length());
cacheResult(result);
} else {
cacheResult();
}
}
revertState();
return (result != null);
}
/**
* Advances this scanner past the current line and returns the input
* that was skipped.
*
* This method returns the rest of the current line, excluding any line
* separator at the end. The position is set to the beginning of the next
* line.
*
* null is returned and the scanner's
* position is unchanged. This method may block waiting for input that
* matches the pattern.
*
* horizon code
* points beyond its current position. Note that a match may be clipped
* by the horizon; that is, an arbitrary match result may have been
* different if the horizon had been larger. The scanner treats the
* horizon as a transparent, non-anchoring bound (see {@link
* Matcher#useTransparentBounds} and {@link Matcher#useAnchoringBounds}).
*
* 0, then the horizon is ignored and
* this method continues to search through the input looking for the
* specified pattern without bound. In this case it may buffer all of
* the input searching for the pattern.
*
* NoSuchElementException by using a pattern that can
* match nothing, e.g., sc.skip("[ \t]*").
*
* @param pattern a string specifying the pattern to skip over
* @return this scanner
* @throws NoSuchElementException if the specified pattern is not found
* @throws IllegalStateException if this scanner is closed
*/
public Scanner skip(Pattern pattern) {
ensureOpen();
if (pattern == null)
throw new NullPointerException();
clearCaches();
// Search for the pattern
while (true) {
String token = matchPatternInBuffer(pattern);
if (token != null) {
matchValid = true;
position = matcher.end();
return this;
}
if (needInput)
readInput();
else
throw new NoSuchElementException();
}
}
/**
* Skips input that matches a pattern constructed from the specified
* string.
*
* InputMismatchException
* if the next token cannot be translated into a valid boolean value.
* If the match is successful, the scanner advances past the input that
* matched.
*
* @return the boolean scanned from the input
* @throws InputMismatchException if the next token is not a valid boolean
* @throws NoSuchElementException if input is exhausted
* @throws IllegalStateException if this scanner is closed
*/
public boolean nextBoolean() {
clearCaches();
return Boolean.parseBoolean(next(boolPattern()));
}
/**
* Returns true if the next token in this scanner's input can be
* interpreted as a byte value in the default radix using the
* {@link #nextByte} method. The scanner does not advance past any input.
*
* @return true if and only if this scanner's next token is a valid
* byte value
* @throws IllegalStateException if this scanner is closed
*/
public boolean hasNextByte() {
return hasNextByte(defaultRadix);
}
/**
* Returns true if the next token in this scanner's input can be
* interpreted as a byte value in the specified radix using the
* {@link #nextByte} method. The scanner does not advance past any input.
*
* @param radix the radix used to interpret the token as a byte value
* @return true if and only if this scanner's next token is a valid
* byte value
* @throws IllegalStateException if this scanner is closed
*/
public boolean hasNextByte(int radix) {
setRadix(radix);
boolean result = hasNext(integerPattern());
if (result) { // Cache it
try {
String s = (matcher.group(SIMPLE_GROUP_INDEX) == null) ?
processIntegerToken(hasNextResult) :
hasNextResult;
typeCache = Byte.parseByte(s, radix);
} catch (NumberFormatException nfe) {
result = false;
}
}
return result;
}
/**
* Scans the next token of the input as a byte.
*
* radix
* is the default radix of this scanner.
*
* @return the byte scanned from the input
* @throws InputMismatchException
* if the next token does not match the Integer
* regular expression, or is out of range
* @throws NoSuchElementException if input is exhausted
* @throws IllegalStateException if this scanner is closed
*/
public byte nextByte() {
return nextByte(defaultRadix);
}
/**
* Scans the next token of the input as a byte.
* This method will throw InputMismatchException
* if the next token cannot be translated into a valid byte value as
* described below. If the translation is successful, the scanner advances
* past the input that matched.
*
* radix
* is the default radix of this scanner.
*
* @return the short scanned from the input
* @throws InputMismatchException
* if the next token does not match the Integer
* regular expression, or is out of range
* @throws NoSuchElementException if input is exhausted
* @throws IllegalStateException if this scanner is closed
*/
public short nextShort() {
return nextShort(defaultRadix);
}
/**
* Scans the next token of the input as a short.
* This method will throw InputMismatchException
* if the next token cannot be translated into a valid short value as
* described below. If the translation is successful, the scanner advances
* past the input that matched.
*
* radix
* is the default radix of this scanner.
*
* @return the int scanned from the input
* @throws InputMismatchException
* if the next token does not match the Integer
* regular expression, or is out of range
* @throws NoSuchElementException if input is exhausted
* @throws IllegalStateException if this scanner is closed
*/
public int nextInt() {
return nextInt(defaultRadix);
}
/**
* Scans the next token of the input as an int.
* This method will throw InputMismatchException
* if the next token cannot be translated into a valid int value as
* described below. If the translation is successful, the scanner advances
* past the input that matched.
*
* radix
* is the default radix of this scanner.
*
* @return the long scanned from the input
* @throws InputMismatchException
* if the next token does not match the Integer
* regular expression, or is out of range
* @throws NoSuchElementException if input is exhausted
* @throws IllegalStateException if this scanner is closed
*/
public long nextLong() {
return nextLong(defaultRadix);
}
/**
* Scans the next token of the input as a long.
* This method will throw InputMismatchException
* if the next token cannot be translated into a valid long value as
* described below. If the translation is successful, the scanner advances
* past the input that matched.
*
* InputMismatchException
* if the next token cannot be translated into a valid float value as
* described below. If the translation is successful, the scanner advances
* past the input that matched.
*
* InputMismatchException
* if the next token cannot be translated into a valid double value.
* If the translation is successful, the scanner advances past the input
* that matched.
*
* BigInteger in the default radix using the
* {@link #nextBigInteger} method. The scanner does not advance past any
* input.
*
* @return true if and only if this scanner's next token is a valid
* BigInteger
* @throws IllegalStateException if this scanner is closed
*/
public boolean hasNextBigInteger() {
return hasNextBigInteger(defaultRadix);
}
/**
* Returns true if the next token in this scanner's input can be
* interpreted as a BigInteger in the specified radix using
* the {@link #nextBigInteger} method. The scanner does not advance past
* any input.
*
* @param radix the radix used to interpret the token as an integer
* @return true if and only if this scanner's next token is a valid
* BigInteger
* @throws IllegalStateException if this scanner is closed
*/
public boolean hasNextBigInteger(int radix) {
setRadix(radix);
boolean result = hasNext(integerPattern());
if (result) { // Cache it
try {
String s = (matcher.group(SIMPLE_GROUP_INDEX) == null) ?
processIntegerToken(hasNextResult) :
hasNextResult;
typeCache = new BigInteger(s, radix);
} catch (NumberFormatException nfe) {
result = false;
}
}
return result;
}
/**
* Scans the next token of the input as a {@link java.math.BigInteger
* BigInteger}.
*
* radix
* is the default radix of this scanner.
*
* @return the BigInteger scanned from the input
* @throws InputMismatchException
* if the next token does not match the Integer
* regular expression, or is out of range
* @throws NoSuchElementException if the input is exhausted
* @throws IllegalStateException if this scanner is closed
*/
public BigInteger nextBigInteger() {
return nextBigInteger(defaultRadix);
}
/**
* Scans the next token of the input as a {@link java.math.BigInteger
* BigInteger}.
*
* BigDecimal using the
* {@link #nextBigDecimal} method. The scanner does not advance past any
* input.
*
* @return true if and only if this scanner's next token is a valid
* BigDecimal
* @throws IllegalStateException if this scanner is closed
*/
public boolean hasNextBigDecimal() {
setRadix(10);
boolean result = hasNext(decimalPattern());
if (result) { // Cache it
try {
String s = processFloatToken(hasNextResult);
typeCache = new BigDecimal(s);
} catch (NumberFormatException nfe) {
result = false;
}
}
return result;
}
/**
* Scans the next token of the input as a {@link java.math.BigDecimal
* BigDecimal}.
*
*
*
* @return this scanner
*
* @since 1.6
*/
public Scanner reset() {
delimPattern = WHITESPACE_PATTERN;
useLocale(Locale.getDefault(Locale.Category.FORMAT));
useRadix(10);
clearCaches();
return this;
}
}
{@code
* scanner.useDelimiter("\\p{javaWhitespace}+")
* .useLocale(Locale.getDefault(Locale.Category.FORMAT))
* .useRadix(10);
* }