Why does runOnUIThread still cause looper.prepare() error message

Question

I have an Android game that uses the Libgdx game engine. I have an Android activity (mAndroidLauncher) that extends Libgdx's AndroidApplication class. There is a method that creates an Android alert dialog:

mAndroidLauncher.runOnUiThread(new Runnable() {
    @Override
    public void run() {
        AlertDialog.Builder builder = new AlertDialog.Builder(mAndroidLauncher.getContext());
        builder.setTitle("Notice");
        builder.setMessage("Alert!!!");
        builder.setNeutralButton("OK", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) {
               //OK
            }
        });
        AlertDialog dialog = builder.create();
        dialog.show();
    }
});

I have a crash in the Google Play Developer Console as follows:

java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
at android.os.Handler.<init>(Handler.java:208)
at android.os.Handler.<init>(Handler.java:122)
at android.app.Dialog.<init>(Dialog.java:109)
at android.app.AlertDialog.<init>(AlertDialog.java:114)
at android.app.AlertDialog$Builder.create(AlertDialog.java:931)
at com.google.android.gms.common.e.a(Unknown Source)
at com.google.android.gms.common.e.a(Unknown Source)
at com.my.game.l.a(Unknown Source)
at com.my.game.l.g(Unknown Source)
at com.my.game.l.c(Unknown Source)
at com.my.game.a.b(Unknown Source)
at com.my.game.b.f.a(Unknown Source)
at com.my.game.q.b(Unknown Source)
at com.badlogic.gdx.backends.android.i.onDrawFrame(Unknown Source)
at android.opengl.GLSurfaceView$GLThread.guardedRun(GLSurfaceView.java:1557)
at android.opengl.GLSurfaceView$GLThread.run(GLSurfaceView.java:1263)

This is the only place in my app that I use an AlertDialog, that is why I am confident that this is the method that is causing the crash. Why would runOnUiThread cause this error? Do I need to do anything else to make sure the AlertDialog is built from a thread with a looper?

EDIT: Thanks CommonsWare. The error is indeed coming from Google Play Services. Specifically I had a call to gameHelper.beginUserInitiatedSignIn() which was not wrapped in runOnUiThread(). Although, strangely, this didn't cause an error for all phones

The code you show did not generate this stack trace. "This is the only place in my app that I use an AlertDialog" -- it is not your `AlertDialog`. It is one from Play Services. — CommonsWare, Dec 06 '16 at 00:25
Thank you for your help. How do you know it is from Play Services? And how/where can I find out what is causing the error? — mrleeboze, Dec 06 '16 at 00:31
"How do you know it is from Play Services?" -- because the crash is coming from `com.google.android.gms.common.e.a()`, and that is Play Services. "And how/where can I find out what is causing the error?" -- if your code, in your stack trace, is `com.my.game`, use ProGuard mapping files to figure out where `com.my.game.l.a()` is. — CommonsWare, Dec 06 '16 at 00:42

score 0 · Answer 1 · answered Dec 06 '16 at 05:49

 new Handler(Looper.getMainLooper()).postDelayed(new Runnable()
            {
                @Override
                public void run()
                {
                    //Do something here
                    AlertDialog.Builder builder = new AlertDialog.Builder(mAndroidLauncher.getContext());
        builder.setTitle("Notice");
        builder.setMessage("Alert!!!");
        builder.setNeutralButton("OK", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) {
               //OK
            }
        });
        AlertDialog dialog = builder.create();
        dialog.show();
                }
            }, 0);

score 0 · Answer 2 · edited Feb 14 '17 at 10:36

you cannot call runOnUIThread(){} directly using Activity name like calling static method...declare one object in mAndroidLauncher as

public static Activity acitivity = this;

and call runOnUIThread as

mAndroidLauncher.activity.runOnUiThread(new Runnable() {
    @Override
    public void run() {
        AlertDialog.Builder builder = new AlertDialog.Builder(mAndroidLauncher.getContext());
        builder.setTitle("Notice");
        builder.setMessage("Alert!!!");
        builder.setNeutralButton("OK", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) {
               //OK
            }
        });
        AlertDialog dialog = builder.create();
        dialog.show();
    }
});

Why does runOnUIThread still cause looper.prepare() error message

2 Answers2