How to debug internal crash of GLSurfaceView?

Question

I'm developing a VR video viewer using Android Cardboard SDK and RajawaliVR ( https://github.com/Rajawali/RajawaliVR )
On some devices I have this crash when returning from sleep (others just show black screen):

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.opengl.GLSurfaceView$GLThread.surfaceCreated()' on a null object reference
    at android.opengl.GLSurfaceView.surfaceCreated(GLSurfaceView.java:523)
    at android.view.SurfaceView.updateWindow(SurfaceView.java:580)
    at android.view.SurfaceView$3.onPreDraw(SurfaceView.java:176)
    at android.view.ViewTreeObserver.dispatchOnPreDraw(ViewTreeObserver.java:944)
    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1970)
    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1061)
    at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5891)
    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
    at android.view.Choreographer.doCallbacks(Choreographer.java:580)
    at android.view.Choreographer.doFrame(Choreographer.java:550)
    at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753)
    at android.os.Handler.handleCallback(Handler.java:739)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:135)
    at android.app.ActivityThread.main(ActivityThread.java:5292)
    at java.lang.reflect.Method.invoke(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:372)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)

As you can see the crash is in the android code, how do I start debugging it?

Answer 1

You have access to the source code, so start with that.

Assuming you're using Lollipop, it's failing on this line :

mGLThread.surfaceCreated();

The error message indicates that mGLThread is null. Doing a simple search for the assignment (" mGLThread = ") with the web browser reveals two instances, the most interesting of which is this one :

public void setRenderer(Renderer renderer) {
    ...
    mGLThread = new GLThread(mThisWeakRef);

Setting some of the complexities aside, mGLThread should be non-null so long as setRenderer() is called. So the first thing to do is check to see if your application is calling setRenderer() (typically in onCreate() ).

Answer 2

If you're following along the Android Developer OpenGL tutorial , it's possible that Android Studio corrected this definition in your Activity class constructor:

mGLView = new MyGLSurfaceView(this);

and changed it to

mGLView = new GLSurfaceView(this);

because the class MyGLSurfaceView had not been coded yet...skipping the MyGLSurfaveView constructor which is where setRenderer(...) is called. Mr. fadden's answer above is excellent, explains how to diagnose the problem.