ChoiceFormat allows you to attach a format to a range of numbers.
* It is generally used in a MessageFormat for handling plurals.
* The choice is specified with an ascending list of doubles, where each item
* specifies a half-open interval up to the next item:
* ** If there is no match, then either the first or last index is used, depending * on whether the number (X) is too low or too high. If the limit array is not * in ascending order, the results of formatting will be incorrect. ChoiceFormat * also accepts* X matches j if and only if limit[j] ≤ X < limit[j+1] **
\u221E as equivalent to infinity(INF).
*
*
* Note:
* ChoiceFormat differs from the other Format
* classes in that you create a ChoiceFormat object with a
* constructor (not with a getInstance style factory
* method). The factory methods aren't necessary because ChoiceFormat
* doesn't require any complex setup for a given locale. In fact,
* ChoiceFormat doesn't implement any locale specific behavior.
*
*
* When creating a ChoiceFormat, you must specify an array of formats
* and an array of limits. The length of these arrays must be the same.
* For example,
*
nextDouble can be used to get the next higher double, to
* make the half-open interval.)
* * Here is a simple example that shows formatting and parsing: *
* {@code
* double[] limits = {1,2,3,4,5,6,7};
* String[] dayOfWeekNames = {"Sun","Mon","Tue","Wed","Thur","Fri","Sat"};
* ChoiceFormat form = new ChoiceFormat(limits, dayOfWeekNames);
* ParsePosition status = new ParsePosition(0);
* for (double i = 0.0; i <= 8.0; ++i) {
* status.setIndex(0);
* System.out.println(i + " -> " + form.format(i) + " -> "
* + form.parse(form.format(i),status));
* }
* }
*
* Here is a more complex example, with a pattern format:
*
* {@code
* double[] filelimits = {0,1,2};
* String[] filepart = {"are no files","is one file","are {2} files"};
* ChoiceFormat fileform = new ChoiceFormat(filelimits, filepart);
* Format[] testFormats = {fileform, null, NumberFormat.getInstance()};
* MessageFormat pattform = new MessageFormat("There {0} on {1}");
* pattform.setFormats(testFormats);
* Object[] testArgs = {null, "ADisk", null};
* for (int i = 0; i < 4; ++i) {
* testArgs[0] = new Integer(i);
* testArgs[2] = testArgs[0];
* System.out.println(pattform.format(testArgs));
* }
* }
*
* * Specifying a pattern for ChoiceFormat objects is fairly straightforward. * For example: *
* {@code
* ChoiceFormat fmt = new ChoiceFormat(
* "-1#is negative| 0#is zero or fraction | 1#is one |1.0
*
* And the output result would be like the following:
*
* {@code
* Format with -INF : is negative
* Format with -1.0 : is negative
* Format with 0 : is zero or fraction
* Format with 0.9 : is zero or fraction
* Format with 1.0 : is one
* Format with 1.5 : is 1+
* Format with 2 : is two
* Format with 2.1 : is more than 2.
* Format with NaN : is negative
* Format with +INF : is more than 2.
* }
*
*
*
* Choice formats are not synchronized.
* It is recommended to create separate format instances for each thread.
* If multiple threads access a format concurrently, it must be synchronized
* externally.
*
*
* @see DecimalFormat
* @see MessageFormat
* @author Mark Davis
*/
public class ChoiceFormat extends NumberFormat {
// Proclaim serial compatibility with 1.1 FCS
private static final long serialVersionUID = 1795184449645032964L;
/**
* Sets the pattern.
* @param newPattern See the class description.
*/
public void applyPattern(String newPattern) {
StringBuffer[] segments = new StringBuffer[2];
for (int i = 0; i < segments.length; ++i) {
segments[i] = new StringBuffer();
}
double[] newChoiceLimits = new double[30];
String[] newChoiceFormats = new String[30];
int count = 0;
int part = 0;
double startValue = 0;
double oldStartValue = Double.NaN;
boolean inQuote = false;
for (int i = 0; i < newPattern.length(); ++i) {
char ch = newPattern.charAt(i);
if (ch=='\'') {
// Check for "''" indicating a literal quote
if ((i+1) Used to make half-open intervals.
*
* @param d the reference value
* @return the least double value greather than {@code d}
* @see #previousDouble
*/
public static final double nextDouble (double d) {
return nextDouble(d,true);
}
/**
* Finds the greatest double less than {@code d}.
* If {@code NaN}, returns same value.
*
* @param d the reference value
* @return the greatest double value less than {@code d}
* @see #nextDouble
*/
public static final double previousDouble (double d) {
return nextDouble(d,false);
}
/**
* Overrides Cloneable
*/
public Object clone()
{
ChoiceFormat other = (ChoiceFormat) super.clone();
// for primitives or immutables, shallow clone is enough
other.choiceLimits = choiceLimits.clone();
other.choiceFormats = choiceFormats.clone();
return other;
}
/**
* Generates a hash code for the message format object.
*/
public int hashCode() {
int result = choiceLimits.length;
if (choiceFormats.length > 0) {
// enough for reasonable distribution
result ^= choiceFormats[choiceFormats.length-1].hashCode();
}
return result;
}
/**
* Equality comparision between two
*/
public boolean equals(Object obj) {
if (obj == null) return false;
if (this == obj) // quick check
return true;
if (getClass() != obj.getClass())
return false;
ChoiceFormat other = (ChoiceFormat) obj;
return (Arrays.equals(choiceLimits, other.choiceLimits)
&& Arrays.equals(choiceFormats, other.choiceFormats));
}
/**
* After reading an object from the input stream, do a simple verification
* to maintain class invariants.
* @throws InvalidObjectException if the objects read from the stream is invalid.
*/
private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
in.defaultReadObject();
if (choiceLimits.length != choiceFormats.length) {
throw new InvalidObjectException(
"limits and format arrays of different length.");
}
}
// ===============privates===========================
/**
* A list of lower bounds for the choices. The formatter will return
* choiceFormats[i] if the number being formatted is greater than or equal to
* choiceLimits[i] and less than choiceLimits[i+1].
* @serial
*/
private double[] choiceLimits;
/**
* A list of choice strings. The formatter will return
* choiceFormats[i] if the number being formatted is greater than or equal to
* choiceLimits[i] and less than choiceLimits[i+1].
* @serial
*/
private String[] choiceFormats;
/*
static final long SIGN = 0x8000000000000000L;
static final long EXPONENT = 0x7FF0000000000000L;
static final long SIGNIFICAND = 0x000FFFFFFFFFFFFFL;
private static double nextDouble (double d, boolean positive) {
if (Double.isNaN(d) || Double.isInfinite(d)) {
return d;
}
long bits = Double.doubleToLongBits(d);
long significand = bits & SIGNIFICAND;
if (bits < 0) {
significand |= (SIGN | EXPONENT);
}
long exponent = bits & EXPONENT;
if (positive) {
significand += 1;
// FIXME fix overflow & underflow
} else {
significand -= 1;
// FIXME fix overflow & underflow
}
bits = exponent | (significand & ~EXPONENT);
return Double.longBitsToDouble(bits);
}
*/
static final long SIGN = 0x8000000000000000L;
static final long EXPONENT = 0x7FF0000000000000L;
static final long POSITIVEINFINITY = 0x7FF0000000000000L;
/**
* Finds the least double greater than {@code d} (if {@code positive} is
* {@code true}), or the greatest double less than {@code d} (if
* {@code positive} is {@code false}).
* If {@code NaN}, returns same value.
*
* Does not affect floating-point flags,
* provided these member functions do not:
* Double.longBitsToDouble(long)
* Double.doubleToLongBits(double)
* Double.isNaN(double)
*
* @param d the reference value
* @param positive {@code true} if the least double is desired;
* {@code false} otherwise
* @return the least or greater double value
*/
public static double nextDouble (double d, boolean positive) {
/* filter out NaN's */
if (Double.isNaN(d)) {
return d;
}
/* zero's are also a special case */
if (d == 0.0) {
double smallestPositiveDouble = Double.longBitsToDouble(1L);
if (positive) {
return smallestPositiveDouble;
} else {
return -smallestPositiveDouble;
}
}
/* if entering here, d is a nonzero value */
/* hold all bits in a long for later use */
long bits = Double.doubleToLongBits(d);
/* strip off the sign bit */
long magnitude = bits & ~SIGN;
/* if next double away from zero, increase magnitude */
if ((bits > 0) == positive) {
if (magnitude != POSITIVEINFINITY) {
magnitude += 1;
}
}
/* else decrease magnitude */
else {
magnitude -= 1;
}
/* restore sign bit and return */
long signbit = bits & SIGN;
return Double.longBitsToDouble (magnitude | signbit);
}
private static double[] doubleArraySize(double[] array) {
int oldSize = array.length;
double[] newArray = new double[oldSize * 2];
System.arraycopy(array, 0, newArray, 0, oldSize);
return newArray;
}
private String[] doubleArraySize(String[] array) {
int oldSize = array.length;
String[] newArray = new String[oldSize * 2];
System.arraycopy(array, 0, newArray, 0, oldSize);
return newArray;
}
}