Note that additional source version constants will be added to
* model future releases of the language.
*
* @author Joseph D. Darcy
* @author Scott Seligman
* @author Peter von der Ahé
* @since 1.6
*/
public enum SourceVersion {
/*
* Summary of language evolution
* 1.1: nested classes
* 1.2: strictfp
* 1.3: no changes
* 1.4: assert
* 1.5: annotations, generics, autoboxing, var-args...
* 1.6: no changes
* 1.7: diamond syntax, try-with-resources, etc.
* 1.8: lambda expressions and default methods
* 1.9: To be determined
*/
/**
* The original version.
*
* The language described in
* The Java™ Language Specification, First Edition.
*/
RELEASE_0,
/**
* The version recognized by the Java Platform 1.1.
*
* The language is {@code RELEASE_0} augmented with nested classes as described in the 1.1 update to
* The Java™ Language Specification, First Edition.
*/
RELEASE_1,
/**
* The version recognized by the Java 2 Platform, Standard Edition,
* v 1.2.
*
* The language described in
* The Java™ Language Specification,
* Second Edition, which includes the {@code
* strictfp} modifier.
*/
RELEASE_2,
/**
* The version recognized by the Java 2 Platform, Standard Edition,
* v 1.3.
*
* No major changes from {@code RELEASE_2}.
*/
RELEASE_3,
/**
* The version recognized by the Java 2 Platform, Standard Edition,
* v 1.4.
*
* Added a simple assertion facility.
*/
RELEASE_4,
/**
* The version recognized by the Java 2 Platform, Standard
* Edition 5.0.
*
* The language described in
* The Java™ Language Specification,
* Third Edition. First release to support
* generics, annotations, autoboxing, var-args, enhanced {@code
* for} loop, and hexadecimal floating-point literals.
*/
RELEASE_5,
/**
* The version recognized by the Java Platform, Standard Edition
* 6.
*
* No major changes from {@code RELEASE_5}.
*/
RELEASE_6,
/**
* The version recognized by the Java Platform, Standard Edition
* 7.
*
* Additions in this release include, diamond syntax for
* constructors, {@code try}-with-resources, strings in switch,
* binary literals, and multi-catch.
* @since 1.7
*/
RELEASE_7,
/**
* The version recognized by the Java Platform, Standard Edition
* 8.
*
* Additions in this release include lambda expressions and default methods.
* @since 1.8
*/
RELEASE_8,
/**
* The version recognized by the Java Platform, Standard Edition
* 9.
*
* @since 1.9
*/
RELEASE_9;
// Note that when adding constants for newer releases, the
// behavior of latest() and latestSupported() must be updated too.
/**
* Returns the latest source version that can be modeled.
*
* @return the latest source version that can be modeled
*/
public static SourceVersion latest() {
return RELEASE_9;
}
private static final SourceVersion latestSupported = getLatestSupported();
private static SourceVersion getLatestSupported() {
try {
String specVersion = System.getProperty("java.specification.version");
switch (specVersion) {
case "9":
return RELEASE_9;
case "1.8":
return RELEASE_8;
case "1.7":
return RELEASE_7;
case "1.6":
return RELEASE_6;
}
} catch (SecurityException se) {}
return RELEASE_5;
}
/**
* Returns the latest source version fully supported by the
* current execution environment. {@code RELEASE_5} or later must
* be returned.
*
* @return the latest source version that is fully supported
*/
public static SourceVersion latestSupported() {
return latestSupported;
}
/**
* Returns whether or not {@code name} is a syntactically valid
* identifier (simple name) or keyword in the latest source
* version. The method returns {@code true} if the name consists
* of an initial character for which {@link
* Character#isJavaIdentifierStart(int)} returns {@code true},
* followed only by characters for which {@link
* Character#isJavaIdentifierPart(int)} returns {@code true}.
* This pattern matches regular identifiers, keywords, and the
* literals {@code "true"}, {@code "false"}, and {@code "null"}.
* The method returns {@code false} for all other strings.
*
* @param name the string to check
* @return {@code true} if this string is a
* syntactically valid identifier or keyword, {@code false}
* otherwise.
*/
public static boolean isIdentifier(CharSequence name) {
String id = name.toString();
if (id.length() == 0) {
return false;
}
int cp = id.codePointAt(0);
if (!Character.isJavaIdentifierStart(cp)) {
return false;
}
for (int i = Character.charCount(cp);
i < id.length();
i += Character.charCount(cp)) {
cp = id.codePointAt(i);
if (!Character.isJavaIdentifierPart(cp)) {
return false;
}
}
return true;
}
/**
* Returns whether or not {@code name} is a syntactically valid
* qualified name in the latest source version. Unlike {@link
* #isIdentifier isIdentifier}, this method returns {@code false}
* for keywords and literals.
*
* @param name the string to check
* @return {@code true} if this string is a
* syntactically valid name, {@code false} otherwise.
* @jls 6.2 Names and Identifiers
*/
public static boolean isName(CharSequence name) {
String id = name.toString();
for(String s : id.split("\\.", -1)) {
if (!isIdentifier(s) || isKeyword(s))
return false;
}
return true;
}
private final static Set