Play developer console: 2 error reports on 13k active users

Question

I have a small question as a starting developer. I've created an app that has been downloaded quite a lot last 2 weeks and has 13k active users. I've tested this on a few (Samsung) phones and of course in the emulator. I can't generate any errors, since the app is simple I wasn't expecting it to do so.

But today I've looked into my Play Developer Console and found 2 error reports. Is this something that I should be concerned about or can this errors be randomly generated? I know for example that bad custom roms can create a crash, I've experienced this myself.

I will post the class that created this, this plays a selected sound when a button is clicked. One of the crashes in a nullPointerException when the button was clicked, the other was a illegalStateException that was generated when mp.stop() was called. To me it seems not possible that this generates an error, but of course I could be wrong. This is the code:

public class SoundActivity extends Activity implements OnClickListener,
    OnCheckedChangeListener {

Button btn;
MediaPlayer mp;
RadioGroup slct;
RadioButton radio0, radio1, radio2, radio3, radio4;
int t = 1;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    setContentView(R.layout.btclayout);
    initialize();
    btn.setOnClickListener(this);
    slct.setOnCheckedChangeListener(this);
    mp = MediaPlayer.create(this, R.raw.sound1);

}

public void initialize() {
    btn = (Button) findViewById(R.id.button1);
    slct = (RadioGroup) findViewById(R.id.radioGroup1);
    radio0 = (RadioButton) findViewById(R.id.radio0);
    radio1 = (RadioButton) findViewById(R.id.radio1);
    radio2 = (RadioButton) findViewById(R.id.radio2);
    radio3 = (RadioButton) findViewById(R.id.radio3);
    radio4 = (RadioButton) findViewById(R.id.radio4);

}

@Override
public void onClick(View v) {
    // TODO Auto-generated method stub
    mp.stop();
    mp.reset();
    switch (t) {
    case 1:
        mp = MediaPlayer.create(this, R.raw.sound1);
        break;
    case 2:
        mp = MediaPlayer.create(this, R.raw.sound2);
        break;
    case 3:
        mp = MediaPlayer.create(this, R.raw.sound3);
        break;
    }
    mp.start();
}

@Override
protected void onPause() {
    // TODO Auto-generated method stub
    super.onPause();
    mp.release();
}

@Override
protected void onResume() {
    // TODO Auto-generated method stub
    super.onResume();
    mp = MediaPlayer.create(this, R.raw.sound1);
}

@Override
public void onCheckedChanged(RadioGroup arg0, int arg1) {
    // TODO Auto-generated method stub
    switch (arg1) {
    case R.id.radio0:
        t = 1;
        break;
    case R.id.radio1:
        t = 2;
        break;
    case R.id.radio2:
        t = 3;
        break;
    case R.id.radio3:
        t = 4;
        break;
    case R.id.radio4:
        t = 5;
        break;
    }
}
}

Edit: This are the stacktraces from the Play Console:

java.lang.IllegalStateException at android.media.MediaPlayer._stop(Native Method) at android.media.MediaPlayer.stop(MediaPlayer.java:1033) at com.ddroid.DisMyApp.SoundActivity.onClick(SoundActivity.java:57) at android.view.View.performClick(View.java:3549) at android.view.View$PerformClick.run(View.java:14400) at android.os.Handler.handleCallback(Handler.java:605) at android.os.Handler.dispatchMessage(Handler.java:92) at android.os.Looper.loop(Looper.java:154) at android.app.ActivityThread.main(ActivityThread.java:4944) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:511) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) at dalvik.system.NativeStart.main(Native Method)

The second one:

java.lang.NullPointerException at com.ddroid.DisMyApp.SoundActivity.onClick(SoundActivity.java:76) at android.view.View.performClick(View.java:2538) at android.view.View$PerformClick.run(View.java:9152) at android.os.Handler.handleCallback(Handler.java:587) at android.os.Handler.dispatchMessage(Handler.java:92) at android.os.Looper.loop(Looper.java:130) at android.app.ActivityThread.main(ActivityThread.java:3687) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:507) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625) at dalvik.system.NativeStart.main(Native Method)

Answer 1

While these errors should not happen, it's been my experience that users will always find a way to crash your application in unintended ways :) In each of these failures, it happened in the onClick() , so I would wrap the onClick() code inside a try/catch and then simply log the error. The fact that you are seeing the error in your developer console means that the user experienced a Force Close issue, so trapping the error is certainly better.

In many State related issues that I've seen, it's mainly to with the the user performing an operation while doing a rotate on the device at the same time. Sometimes using the Android Monkey can randomly simulate these kinds of errors as well.