Android Renderer calls

OK so i tried asking this on StackOverflow, but that came up with nothing, so this seemed the next best place to ask.

Not quite sure what’s going on, I’ve been following the stuff in the book Pro Android 2, but I can’t get this to work, and the book’s not much help on it. It’s just a test thing I’m doing to try out the GLES stuff, but it refuses to call the onDrawFrame, onSurfaceCreated and onSurfaceChanged methods. I passed round a TextView object and had every method add a line when it gets run, but the only things being run are the main activity and the constructor method for the renderer.

public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        
        tv = new TextView(this);
        
        testSurface = new GLSurfaceView(this);
        
        //testSurface.setEGLConfigChooser(false);
        testSurface.setRenderer(new Renderer(this, tv));
        testSurface.setRenderMode(GLSurfaceView.RENDERMODE_CONTINUOUSLY);
        //testSurface.setRenderMode(GLSurfaceView.RENDERMODE_WHEN_DIRTY);
        
        setContentView(testSurface);
        
        try{
        Thread.sleep(50000);}
        catch(Exception e){}
        
        tv.setText(tv.getText() + "\nFinished.");
        
        setContentView(tv);

Is the code in the activity. The Renderer constructor doesn’t do anything more than set up a couple of vertices in a buffer to be drawn. Anyone any ideas about why the Rendering methods aren’t being called? Some small line I’ve missed or something? I’ve tried looking at other sources of example code but can’t find anything in it different that could be setting off the rendering.