Question

I currently have a project in which the main activity launches another activity for information gathering and then goes back to the main activity. I am trying to handle the back button press. Every time I execute the following code it crashes. But I don’t understand why.

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) {

        finish();
        return true;
    }
    return super.onKeyDown(keyCode, event);
};

I have also tried:

@Override
    public void onBackPressed() {
            finish();
    };

Stack trace:

09-14 15:30:13.740: E/AndroidRuntime(32400): FATAL EXCEPTION: main
09-14 15:30:13.740: E/AndroidRuntime(32400): java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=2, result=0, data=null} to activity {peaBerry.Shopping.Consultant/peaBerry.Shopping.Consultant.PeaBerryTeaActivity}: java.lang.NullPointerException
09-14 15:30:13.740: E/AndroidRuntime(32400):    at android.app.ActivityThread.deliverResults(ActivityThread.java:2655)
09-14 15:30:13.740: E/AndroidRuntime(32400):    at android.app.ActivityThread.handleSendResult(ActivityThread.java:2697)
09-14 15:30:13.740: E/AndroidRuntime(32400):    at android.app.ActivityThread.access$2000(ActivityThread.java:124)
09-14 15:30:13.740: E/AndroidRuntime(32400):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:998)
09-14 15:30:13.740: E/AndroidRuntime(32400):    at android.os.Handler.dispatchMessage(Handler.java:99)
09-14 15:30:13.740: E/AndroidRuntime(32400):    at android.os.Looper.loop(Looper.java:130)
09-14 15:30:13.740: E/AndroidRuntime(32400):    at android.app.ActivityThread.main(ActivityThread.java:3806)
09-14 15:30:13.740: E/AndroidRuntime(32400):    at java.lang.reflect.Method.invokeNative(Native Method)
09-14 15:30:13.740: E/AndroidRuntime(32400):    at java.lang.reflect.Method.invoke(Method.java:507)
09-14 15:30:13.740: E/AndroidRuntime(32400):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
09-14 15:30:13.740: E/AndroidRuntime(32400):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
09-14 15:30:13.740: E/AndroidRuntime(32400):    at dalvik.system.NativeStart.main(Native Method)
09-14 15:30:13.740: E/AndroidRuntime(32400): Caused by: java.lang.NullPointerException
09-14 15:30:13.740: E/AndroidRuntime(32400):    at peaBerry.Shopping.Consultant.PeaBerryTeaActivity.onActivityResult(PeaBerryTeaActivity.java:312)
09-14 15:30:13.740: E/AndroidRuntime(32400):    at android.app.Activity.dispatchActivityResult(Activity.java:3958)
09-14 15:30:13.740: E/AndroidRuntime(32400):    at android.app.ActivityThread.deliverResults(ActivityThread.java:2651)

Answer 1

According to the error message, a result is missing. Have you started the 2nd Activity with startActivityForResult()? If so, add a setResult(value) or setResult(value, data) before calling finish() in your 2nd Activity, to pass back the expected result to the calling Activity.