libgdx/libgdx · error · UnsupportedOperationException

UnsupportedOperationException

Error message

UnsupportedOperationException

What it means

DirectReadWriteShortBufferAdapter — the ShortBuffer view of a GWT emulated direct ByteBuffer (asShortBuffer()) — throws UnsupportedOperationException from protectedArray() because a direct view has no short[] backing array. The emulated ShortBuffer.array() delegates to this method, so any array() call on the view throws. protectedHasArray() returns false, so hasArray() is the correct pre-check.

Source

Thrown at backends/gdx-backends-gwt/src/com/badlogic/gdx/backends/gwt/emu/java/nio/DirectReadWriteShortBufferAdapter.java:116

	@Override
	public boolean isDirect () {
		return true;
	}

	@Override
	public boolean isReadOnly () {
		return false;
	}

	@Override
	public ByteOrder order () {
		return byteBuffer.order();
	}

	@Override
	protected short[] protectedArray () {
		throw new UnsupportedOperationException();
	}

	@Override
	protected int protectedArrayOffset () {
		throw new UnsupportedOperationException();
	}

	@Override
	protected boolean protectedHasArray () {
		return false;
	}

	@Override
	public ShortBuffer put (short c) {
// if (position == limit) {
// throw new BufferOverflowException();
// }
		shortArray.set(position++, c);

View on GitHub (pinned to 97f4086187)

Solutions

1. Check sb.hasArray() first; for direct views, bulk-copy with sb.get(short[]) or use relative/absolute puts.
2. Build data in a short[] then ShortBuffer.wrap(arr) or use put(short[]) instead of exposing the internal array.
3. Use libGDX's ShortArray or number-utils array helpers on GWT instead of nio array access.

Example fix

// before
short[] verts = sb.array(); // UnsupportedOperationException

// after
short[] verts = new short[sb.remaining()];
sb.get(verts);

if (sb.hasArray()) {
  short[] arr = sb.array();
} else {
  short[] arr = new short[sb.remaining()];
  sb.get(arr);
}

boolean isHeapBacked(ShortBuffer sb) {
  return sb != null && sb.hasArray();
}

try {
  short[] a = sb.array();
} catch (UnsupportedOperationException e) {
  short[] a = new short[sb.remaining()];
  sb.get(a);
}

When it happens

Trigger: Calling shortBuffer.array() on a ShortBuffer from ByteBuffer.asShortBuffer() in a GWT build; typical in vertex-data builders that memcpy from the raw array, or audio code that assumed a heap buffer.

Common situations: Mesh construction via FloatBuffer/ShortBuffer views that worked on desktop JVM direct buffers with array() hacks; libraries calling array() without checking hasArray().

Related errors

• UnsupportedOperationException
• UnsupportedOperationException
• BufferOverflowException
• ReadOnlyBufferException
• BufferUnderflowException

AI-assisted analysis of libgdx/libgdx@97f4086187 (2026-08-14). Data as JSON: /api/errors/be923eee7cadffc2. Report an issue: GitHub.