src/java.compiler/share/classes/javax/lang/model/SourceVersion.java

*** 1,7 ****
  /*
!  * Copyright (c) 2005, 2015, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
--- 1,7 ----
  /*
!  * Copyright (c) 2005, 2016, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
*** 53,63 ****
       * 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
!      * 9: To be determined
       */
  
      /**
       * The original version.
       *
--- 53,63 ----
       * 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
!      *   9: modules, small cleanups to 1.7 and 1.8 changes
       */
  
      /**
       * The original version.
       *
*** 143,152 ****
--- 143,155 ----
  
      /**
       * The version recognized by the Java Platform, Standard Edition
       * 9.
       *
+      * Additions in this release include modules and removal of a
+      * single underscore from the set of legal identifier names.
+      *
       * @since 9
       */
       RELEASE_9;
  
      // Note that when adding constants for newer releases, the
*** 242,255 ****
       * @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;
      }
  
--- 245,275 ----
       * @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) {
+         return isName(name, latest());
+     }
+ 
+     /**
+      * Returns whether or not {@code name} is a syntactically valid
+      * qualified name in the given source version.  Unlike {@link
+      * #isIdentifier isIdentifier}, this method returns {@code false}
+      * for keywords and literals.
+      *
+      * @param name the string to check
+      * @param version the version to use
+      * @return {@code true} if this string is a
+      * syntactically valid name, {@code false} otherwise.
+      * @jls 6.2 Names and Identifiers
+      * @since 9
+      */
+     public static boolean isName(CharSequence name, SourceVersion version) {
          String id = name.toString();
  
          for(String s : id.split("\\.", -1)) {
!             if (!isIdentifier(s) || isKeyword(s, version))
                  return false;
          }
          return true;
      }
  
*** 266,276 ****
              "catch",    "extends",      "int",          "short",        "try",
              "char",     "final",        "interface",    "static",       "void",
              "class",    "finally",      "long",         "strictfp",     "volatile",
              "const",    "float",        "native",       "super",        "while",
              // literals
!             "null",     "true",         "false"
          };
          for(String kw : kws)
              s.add(kw);
          keywords = Collections.unmodifiableSet(s);
      }
--- 286,297 ----
              "catch",    "extends",      "int",          "short",        "try",
              "char",     "final",        "interface",    "static",       "void",
              "class",    "finally",      "long",         "strictfp",     "volatile",
              "const",    "float",        "native",       "super",        "while",
              // literals
!             "null",     "true",         "false",
!             "_" // keyword as of 9
          };
          for(String kw : kws)
              s.add(kw);
          keywords = Collections.unmodifiableSet(s);
      }
*** 283,288 ****
--- 304,327 ----
       * @return {@code true} if {@code s} is a keyword or literal, {@code false} otherwise.
       */
      public static boolean isKeyword(CharSequence s) {
          return keywords.contains(s.toString());
      }
+ 
+     /**
+      * Returns whether or not {@code s} is a keyword or literal in the
+      * given source version.
+      *
+      * @param s the string to check
+      * @param version the version to use
+      * @return {@code true} if {@code s} is a keyword or literal, {@code false} otherwise.
+      * @since 9
+      */
+     public static boolean isKeyword(CharSequence s, SourceVersion version) {
+         String id = s.toString();
+         if ("_".equals(id)) {
+             return version.compareTo(RELEASE_9) >= 0;
+         } else {
+             return keywords.contains(id);
+         }
+     }
  }