Implemented the file identifier functionality for Java.

Also fixed flatc not outputting these identifiers for files
compiled on the command-line.

Bug: 16983987
Change-Id: I8b714cfea3a8e144fa52133f62b2f7eda6eb044a
Tested: on Linux

tests/JavaTest.java

@@ -85,7 +85,7 @@ class JavaTest {
         Monster.addTestarrayofstring(fbb, testArrayOfString);
         int mon = Monster.endMonster(fbb);
 
-        fbb.finish(mon);
+        Monster.finishMonsterBuffer(fbb, mon);
 
         // Write the result to a file for debugging purposes:
         // Note that the binaries are not necessarily identical, since the JSON
@@ -113,6 +113,8 @@ class JavaTest {
     }
 
     static void TestBuffer(ByteBuffer bb, int start) {
+        TestEq(Monster.MonsterBufferHasIdentifier(bb, start), true);
+
         Monster monster = Monster.getRootAsMonster(bb, start);
 
         TestEq(monster.hp(), (short)80);

tests/MyGame/Example/Monster.java

@@ -9,7 +9,9 @@ import flatbuffers.*;
 
 public class Monster extends Table {
   public static Monster getRootAsMonster(ByteBuffer _bb, int offset) { _bb.order(ByteOrder.LITTLE_ENDIAN); return (new Monster()).__init(_bb.getInt(offset) + offset, _bb); }
+  public static boolean MonsterBufferHasIdentifier(ByteBuffer _bb, int offset) { return __has_identifier(_bb, offset, "MONS"); }
   public Monster __init(int _i, ByteBuffer _bb) { bb_pos = _i; bb = _bb; return this; }
+
   public Vec3 pos() { return pos(new Vec3()); }
   public Vec3 pos(Vec3 obj) { int o = __offset(4); return o != 0 ? obj.__init(o + bb_pos, bb) : null; }
   public short mana() { int o = __offset(6); return o != 0 ? bb.getShort(o + bb_pos) : 150; }
@@ -57,5 +59,6 @@ public class Monster extends Table {
   public static void startTestnestedflatbufferVector(FlatBufferBuilder builder, int numElems) { builder.startVector(1, numElems, 1); }
   public static void addTestempty(FlatBufferBuilder builder, int testemptyOffset) { builder.addOffset(14, testemptyOffset, 0); }
   public static int endMonster(FlatBufferBuilder builder) { return builder.endObject(); }
+  public static void finishMonsterBuffer(FlatBufferBuilder builder, int offset) { builder.finish(offset, "MONS"); }
 };
 

tests/MyGame/Example/Test.java

@@ -9,6 +9,7 @@ import flatbuffers.*;
 
 public class Test extends Struct {
   public Test __init(int _i, ByteBuffer _bb) { bb_pos = _i; bb = _bb; return this; }
+
   public short a() { return bb.getShort(bb_pos + 0); }
   public byte b() { return bb.get(bb_pos + 2); }
 

tests/MyGame/Example/Vec3.java

@@ -9,6 +9,7 @@ import flatbuffers.*;
 
 public class Vec3 extends Struct {
   public Vec3 __init(int _i, ByteBuffer _bb) { bb_pos = _i; bb = _bb; return this; }
+
   public float x() { return bb.getFloat(bb_pos + 0); }
   public float y() { return bb.getFloat(bb_pos + 4); }
   public float z() { return bb.getFloat(bb_pos + 8); }

tests/monsterdata_test.json

@@ -32,5 +32,9 @@
       a: 30,
       b: 40
     }
+  ],
+  testarrayofstring: [
+    "test1",
+    "test2"
   ]
 }