Thread thread = new Thread ( new Runnable () { // <- Never override classes if it is not required. public void run () { GameLevel appLevel = new GameLevel (levelName,id,x,y,z); appLevel.setEnabled( true ); app.enqueue( new Runnable () { @Override public void run () { app.getStateManager().attach(appLevel); app.getGuiNode().detachChild(pic); } }); } });