Android app crashes when the orientation changes

Question

This app crashes when the orientation changes, specially in the state there i can give the variables back there value. But in my case i just want to empty the variable mp. When i add mp.reset() the app begins to crash when i rotate the phone.

package com.phone.sensor;

import android.app.Activity;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.view.Menu;
import android.widget.TextView;

public class sensorActivity extends Activity implements SensorEventListener{
    public boolean musStatus = false;
    public boolean musDeclare = false;
    public MediaPlayer mp;

    Sensor accelerometer;
    SensorManager sm;
    TextView acceleration;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if(savedInstanceState==null)
        {
            musDeclare = false;
            musStatus = false;
            mp = null;
        }
        else 
        {
            mp.reset();
        }

        setContentView(R.layout.activity_main);
        sm=(SensorManager) getSystemService(SENSOR_SERVICE);
        accelerometer=sm.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
        sm.registerListener(this, accelerometer, SensorManager.SENSOR_DELAY_NORMAL);

        acceleration=(TextView)findViewById(R.id.acceleration);
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }


    @Override
    public void onAccuracyChanged(Sensor sensor, int accuracy) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onSaveInstanceState (Bundle outState)
    {
        super.onSaveInstanceState(outState);
        outState.putBoolean("musStatus", musStatus);
        outState.putBoolean("musDeclare", musDeclare);
    }

    @Override
    public void onSensorChanged(SensorEvent event) {
        // TODO Auto-generated method stub
        acceleration.setText("X: "+event.values[0]+
                "\nY: "+event.values[1]+
                "\nZ: "+event.values[2]);

        float x = event.values[0];
        float y = event.values[1];
        float z = event.values[2];

        if(musDeclare == false)
        {
            mp = MediaPlayer.create(this, R.raw.alexander);
            musDeclare = true;
        }

        if(y > 8.9) {           
            if(musStatus == false)
            {
                mp.start();
                musStatus = true;
            } 
        }

        if(y < 5)
        {
            if(musStatus == true)
            {
                mp.stop();
                musStatus = false;

                if(musDeclare == true)
                {
                    mp = MediaPlayer.create(this, R.raw.alexander);
                    musDeclare = false;
                }
            }
        }
    }
}

Logcat

10-06 01:30:37.105: E/AndroidRuntime(15258): FATAL EXCEPTION: main
10-06 01:30:37.105: E/AndroidRuntime(15258): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.phone.sensor/com.phone.sensor.sensorActivity}: java.lang.NullPointerException
10-06 01:30:37.105: E/AndroidRuntime(15258):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2460)
10-06 01:30:37.105: E/AndroidRuntime(15258):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2521)
10-06 01:30:37.105: E/AndroidRuntime(15258):    at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:4260)
10-06 01:30:37.105: E/AndroidRuntime(15258):    at android.app.ActivityThread.access$700(ActivityThread.java:162)
10-06 01:30:37.105: E/AndroidRuntime(15258):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1376)
10-06 01:30:37.105: E/AndroidRuntime(15258):    at android.os.Handler.dispatchMessage(Handler.java:99)
10-06 01:30:37.105: E/AndroidRuntime(15258):    at android.os.Looper.loop(Looper.java:158)
10-06 01:30:37.105: E/AndroidRuntime(15258):    at android.app.ActivityThread.main(ActivityThread.java:5777)
10-06 01:30:37.105: E/AndroidRuntime(15258):    at java.lang.reflect.Method.invokeNative(Native Method)
10-06 01:30:37.105: E/AndroidRuntime(15258):    at java.lang.reflect.Method.invoke(Method.java:511)
10-06 01:30:37.105: E/AndroidRuntime(15258):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1083)
10-06 01:30:37.105: E/AndroidRuntime(15258):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:850)
10-06 01:30:37.105: E/AndroidRuntime(15258):    at dalvik.system.NativeStart.main(Native Method)
10-06 01:30:37.105: E/AndroidRuntime(15258): Caused by: java.lang.NullPointerException
10-06 01:30:37.105: E/AndroidRuntime(15258):    at com.phone.sensor.sensorActivity.onCreate(sensorActivity.java:33)
10-06 01:30:37.105: E/AndroidRuntime(15258):    at android.app.Activity.performCreate(Activity.java:5165)
10-06 01:30:37.105: E/AndroidRuntime(15258):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1103)
10-06 01:30:37.105: E/AndroidRuntime(15258):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
10-06 01:30:37.105: E/AndroidRuntime(15258):    ... 12 more

Everytime an Activity` changes orientation, it reloads the views. Is your app crashing while it's playing and changing orientation? — Si8, Oct 05 '13 at 23:23
In my app, when i have the phone portrait the music plays fine, when i rotate the phone to landscape the music stops and the app crashes. @SiKni8 — G unitzo, Oct 05 '13 at 23:26

score 0 · Answer 1 · edited May 23 '17 at 12:21

0

Im no guru but it fells like you could save your mp in:

@Override
public Object onRetainCustomNonConfigurationInstance() {
    return this.mp;
}

and in onCreate() you will get it back like his

mp = (MediaPlayer) getLastCustomNonConfigurationInstance();

Check this out because trying to keep the MediaPlayer alive in an Activity is surrounded with problems

edited May 23 '17 at 12:21

Community

1
1

answered Oct 05 '13 at 23:28

Erik

5,039
10
63
119

score 0 · Answer 2 · answered Oct 05 '13 at 23:30

0

Try to use the following function to reset your music player:

private MediaPlayer mpSound;
    private void stopPlaying() {
        if (mpSound != null) {
            mpSound.stop();
            mpSound.release();
            mpSound = null;
       }
    }

Calling that each time ensures the sound is set to null and released so the next time it plays, your app doesn't crash (in this case when it changes orientation)

I had similar issue with my app and the above code fixed it.

answered Oct 05 '13 at 23:30

Si8

9,141
22
109
221

This solution helped me with keeping the app alive and thats great, but the problem now is that the sound dubblicates and plays at the same time. That means mp is nu reinitialize @sikni8 – G unitzo Oct 05 '13 at 23:55
As the Logcat suggests the relaunch of the activity is causing the error of you playing the sound. – Si8 Oct 06 '13 at 00:48

Android app crashes when the orientation changes

2 Answers2