src/share/classes/com/sun/tools/javac/code/Source.java

@@ -65,12 +65,15 @@
     JDK1_6("1.6"),
 
     /** 1.7 introduced try-with-resources, multi-catch, string switch, etc. */
     JDK1_7("1.7"),
 
-    /** 1.8 covers the to be determined language features that will be added in JDK 8. */
-    JDK1_8("1.8");
+    /** 1.8 lambda expressions and default methods. */
+    JDK1_8("1.8"),
+
+    /** 1.9 covers the to be determined language features that will be added in JDK 9. */
+    JDK1_9("1.9");
 
     private static final Context.Key<Source> sourceKey
         = new Context.Key<Source>();
 
     public static Source instance(Context context) {

@@ -85,32 +88,34 @@
         return instance;
     }
 
     public final String name;
 
-    private static final Map<String,Source> tab = new HashMap<String,Source>();
+    private static final Map<String,Source> tab = new HashMap<>();
     static {
         for (Source s : values()) {
             tab.put(s.name, s);
         }
         tab.put("5", JDK1_5); // Make 5 an alias for 1.5
         tab.put("6", JDK1_6); // Make 6 an alias for 1.6
         tab.put("7", JDK1_7); // Make 7 an alias for 1.7
         tab.put("8", JDK1_8); // Make 8 an alias for 1.8
+        tab.put("9", JDK1_9); // Make 9 an alias for 1.9
     }
 
     private Source(String name) {
         this.name = name;
     }
 
-    public static final Source DEFAULT = JDK1_8;
+    public static final Source DEFAULT = JDK1_9;
 
     public static Source lookup(String name) {
         return tab.get(name);
     }
 
     public Target requiredTarget() {
+        if (this.compareTo(JDK1_9) >= 0) return Target.JDK1_9;
         if (this.compareTo(JDK1_8) >= 0) return Target.JDK1_8;
         if (this.compareTo(JDK1_7) >= 0) return Target.JDK1_7;
         if (this.compareTo(JDK1_6) >= 0) return Target.JDK1_6;
         if (this.compareTo(JDK1_5) >= 0) return Target.JDK1_5;
         if (this.compareTo(JDK1_4) >= 0) return Target.JDK1_4;

@@ -241,10 +246,12 @@
             return RELEASE_6;
         case JDK1_7:
             return RELEASE_7;
         case JDK1_8:
             return RELEASE_8;
+        case JDK1_9:
+            return RELEASE_8; // Adjust once RELEASE_9 exists
         default:
             return null;
         }
     }
 }