Removed the use of b.array() to support DirectBuffers.

Also removed Table extend Constants.

Change-Id: I1770b613c58094fa572a3b26a31f01bd5fb8fdbf

java/flatbuffers/FlatBufferBuilder.java

@@ -16,7 +16,7 @@
 
 package flatbuffers;
 
-import java.lang.String;
+import static flatbuffers.Constants.*;
 import java.util.Arrays;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
@@ -25,7 +25,7 @@ import java.nio.charset.Charset;
 // Class that helps you build a FlatBuffer.
 // See the section "Use in Java" in the main FlatBuffers documentation.
 
-public class FlatBufferBuilder extends Constants {
+public class FlatBufferBuilder {
     ByteBuffer bb;       // Where we construct the FlatBuffer.
     int space;           // Remaining space in the ByteBuffer.
     static final Charset utf8charset = Charset.forName("UTF-8");
@@ -40,37 +40,34 @@ public class FlatBufferBuilder extends Constants {
     public FlatBufferBuilder(int initial_size) {
         if (initial_size <= 0) initial_size = 1;
         space = initial_size;
-        bb = newByteBuffer(new byte[initial_size]);
+        bb = newByteBuffer(initial_size);
     }
 
     // Alternative constructor allowing reuse of ByteBuffers
     public FlatBufferBuilder(ByteBuffer existing_bb) {
-        if (!existing_bb.hasArray())
-            throw new AssertionError("FlatBuffers: ByteBuffer must have backing array.");
         bb = existing_bb;
         bb.clear();
         bb.order(ByteOrder.LITTLE_ENDIAN);
         space = bb.capacity();
     }
 
-    ByteBuffer newByteBuffer(byte[] buf) {
-        ByteBuffer newbb = ByteBuffer.wrap(buf);
+    static ByteBuffer newByteBuffer(int capacity) {
+        ByteBuffer newbb = ByteBuffer.allocate(capacity);
         newbb.order(ByteOrder.LITTLE_ENDIAN);
         return newbb;
     }
 
     // Doubles the size of the ByteBuffer, and copies the old data towards the
     // end of the new buffer (since we build the buffer backwards).
-    ByteBuffer growByteBuffer(ByteBuffer bb) {
-        byte[] old_buf = bb.array();
-        int old_buf_size = old_buf.length;
+    static ByteBuffer growByteBuffer(ByteBuffer bb) {
+        int old_buf_size = bb.capacity();
         if ((old_buf_size & 0xC0000000) != 0)  // Ensure we don't grow beyond what fits in an int.
             throw new AssertionError("FlatBuffers: cannot grow buffer beyond 2 gigabytes.");
         int new_buf_size = old_buf_size << 1;
-        byte[] new_buf = new byte[new_buf_size];
-        System.arraycopy(old_buf, 0, new_buf, new_buf_size - old_buf_size, old_buf_size);
-        ByteBuffer nbb = newByteBuffer(new_buf);
-        nbb.position(bb.position());
+        bb.position(0);
+        ByteBuffer nbb = newByteBuffer(new_buf_size);
+        nbb.position(new_buf_size - old_buf_size);
+        nbb.put(bb);
         return nbb;
     }
 
@@ -145,7 +142,8 @@ public class FlatBufferBuilder extends Constants {
         byte[] utf8 = s.getBytes(utf8charset);
         addByte((byte)0);
         startVector(1, utf8.length, 1);
-        System.arraycopy(utf8, 0, bb.array(), space -= utf8.length, utf8.length);
+        bb.position(space -= utf8.length);
+        bb.put(utf8, 0, utf8.length);
         return endVector();
     }
 
@@ -267,8 +265,15 @@ public class FlatBufferBuilder extends Constants {
         return space;
     }
 
+    public byte[] sizedByteArray(int start, int length){
+        byte[] array = new byte[length];
+        bb.position(start);
+        bb.get(array);
+        return array;
+    }
+
     // Utility function for copying a byte array that starts at 0.
-    public byte[] sizedByteArray() {
-        return Arrays.copyOfRange(bb.array(), dataStart(), bb.capacity());
+    public byte[] sizedByteArray(){
+        return sizedByteArray(space, bb.capacity() - space);
     }
 }

java/flatbuffers/Table.java

@@ -16,12 +16,12 @@
 
 package flatbuffers;
 
-import java.lang.String;
+import static flatbuffers.Constants.*;
 import java.nio.ByteBuffer;
 import java.nio.charset.Charset;
 
 // All tables in the generated code derive from this class, and add their own accessors.
-public class Table extends Constants {
+public class Table {
   protected int bb_pos;
   protected ByteBuffer bb;
 

tests/JavaTest.java

@@ -105,8 +105,9 @@ class JavaTest {
         // Test it:
         TestBuffer(fbb.dataBuffer(), fbb.dataStart());
 
-        // Make sure it also works with read only ByteBuffers. This is slower, since
-        // creating strings incurs an additional copy (see Table.__string).
+        // Make sure it also works with read only ByteBuffers. This is slower,
+        // since creating strings incurs an additional copy
+        // (see Table.__string).
         TestBuffer(fbb.dataBuffer().asReadOnlyBuffer(), fbb.dataStart());
 
         System.out.println("FlatBuffers test: completed successfully");