libgdx/libgdx · error · UnsupportedOperationException

UnsupportedOperationException

Error message

UnsupportedOperationException

What it means

Thrown by FloatToByteBufferAdapter.protectedArray(), which backs the public array() accessor. Adapter buffers have no float[] backing array — their storage lives in a ByteBuffer — so any attempt to obtain the array throws UnsupportedOperationException, consistent with hasArray() returning false. This is by design, not corruption.

Source

Thrown at backends/gdx-backends-gwt/src/com/badlogic/gdx/backends/gwt/emu/java/nio/FloatToByteBufferAdapter.java:162

	@Override
	public boolean isDirect () {
		return byteBuffer.isDirect();
	}

	@Override
	public boolean isReadOnly () {
		return byteBuffer.isReadOnly();
	}

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

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

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

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

	@Override
	public FloatBuffer put (float c) {
		if (position == limit) {
			throw new BufferOverflowException();
		}
		byteBuffer.putFloat(position++ << 2, c);

View on GitHub (pinned to 97f4086187)

Solutions

1. Check hasArray() before calling array() and take a copy path when false: if (buf.hasArray()) use buf.array() else copy via get(float[]).
2. Replace array() access with a bulk read: float[] out = new float[buf.remaining()]; buf.get(out);
3. Construct the buffer with FloatBuffer.allocate() or FloatBuffer.wrap(float[]) when array access is required.
4. Catch UnsupportedOperationException and degrade gracefully if you cannot change the call site.

Example fix

// before
float[] data = buf.array(); // UnsupportedOperationException on adapter buffers

// after
float[] data = new float[buf.remaining()];
buf.get(data);

// before buf.array()
if (!buf.hasArray()) {
    // adapter buffer: no float[] backing
    float[] copy = new float[buf.remaining()];
    buf.get(copy);
    // use copy
} else {
    float[] arr = buf.array();
}

static boolean hasFloatArray(FloatBuffer b) { return b != null && b.hasArray(); }

try { float[] a = buf.array(); } catch (UnsupportedOperationException e) { /* no backing array: copy via get(float[]) */ }

When it happens

Trigger: Calling array() (or code that calls it, e.g. some serialization or IO helpers) on a FloatBuffer created through FloatToByteBufferAdapter rather than FloatBuffer.allocate/wrap.

Common situations: Utility code that assumes array() works because it was tested with heap FloatBuffers; switching a GWT renderer from array-backed buffers to ByteBuffer-adapter buffers for direct-memory semantics; third-party libraries (e.g. JSON or mesh serializers) calling array() internally.

Related errors

• libGDX requires Android API Level " + MINIMUM_SDK + " or lat
• FileType '
• file() not supported in GWT backend
• Cannot map files in GWT backend
• Cannot write to files in GWT backend

AI-assisted analysis of libgdx/libgdx@97f4086187 (2026-08-14). Data as JSON: /api/errors/4839044d00aa558f. Report an issue: GitHub.