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POHow to solve NullPointerException error in Android?
 

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  1. POHow to solve NullPointerException error in Android?
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    <p>The below code runs smoothly in the emulator from Eclipse, but there are problems when I run it on my Android phone and tablet.</p> <pre><code>public class RingerActivity extends Activity{ /** Called when the activity is first created. */ Button press; boolean tone = true; MediaPlayer mp; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); mp = new MediaPlayer(); mp = MediaPlayer.create(RingerActivity.this, R.raw.alarm); //Error occurs at here mp.start(); Handler h = new Handler(); Runnable stopPlaybackRun = new Runnable() { public void run(){ mp.stop(); mp.release(); } }; h.postDelayed(stopPlaybackRun, 20 * 1000); AudioManager manager = (AudioManager)getSystemService(AUDIO_SERVICE); if(manager!=null){ manager.setRingerMode(AudioManager.RINGER_MODE_NORMAL); int maxVolume = manager.getStreamMaxVolume(AudioManager.STREAM_MUSIC); manager.setStreamVolume(AudioManager.STREAM_MUSIC, maxVolume, 0); } } @Override public boolean onKeyDown(int keyCode, KeyEvent event){ if (keyCode == KeyEvent.KEYCODE_VOLUME_UP){ Toast.makeText(this, "Volume Up", Toast.LENGTH_LONG).show(); return true; } if (keyCode == KeyEvent.KEYCODE_VOLUME_DOWN){ Toast.makeText(this, "Volume Down", Toast.LENGTH_LONG).show(); return true; } return super.onKeyDown(keyCode, event); } </code></pre> <p>I get a "NullPointException" in line "mp.start()". I have been working on this problem for a while, but I really do not know what is happening, I tried this on both my Android smartphone and tablet (Gingerbread and ICS), but the app force closes. I need help from you guys... thanks...</p> <p>Logcat</p> <pre><code>11-09 15:41:09.909: E/AndroidRuntime(11975): FATAL EXCEPTION: main 11-09 15:41:09.909: E/AndroidRuntime(11975): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.testing.ringer/com.testing.ringer.RingerActivity}: java.lang.NullPointerException 11-09 15:41:09.909: E/AndroidRuntime(11975): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1872) 11-09 15:41:09.909: E/AndroidRuntime(11975): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1893) 11-09 15:41:09.909: E/AndroidRuntime(11975): at android.app.ActivityThread.access$1500(ActivityThread.java:135) 11-09 15:41:09.909: E/AndroidRuntime(11975): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1054) 11-09 15:41:09.909: E/AndroidRuntime(11975): at android.os.Handler.dispatchMessage(Handler.java:99) 11-09 15:41:09.909: E/AndroidRuntime(11975): at android.os.Looper.loop(Looper.java:150) 11-09 15:41:09.909: E/AndroidRuntime(11975): at android.app.ActivityThread.main(ActivityThread.java:4385) 11-09 15:41:09.909: E/AndroidRuntime(11975): at java.lang.reflect.Method.invokeNative(Native Method) 11-09 15:41:09.909: E/AndroidRuntime(11975): at java.lang.reflect.Method.invoke(Method.java:507) 11-09 15:41:09.909: E/AndroidRuntime(11975): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:849) 11-09 15:41:09.909: E/AndroidRuntime(11975): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:607) 11-09 15:41:09.909: E/AndroidRuntime(11975): at dalvik.system.NativeStart.main(Native Method) 11-09 15:41:09.909: E/AndroidRuntime(11975): Caused by: java.lang.NullPointerException 11-09 15:41:09.909: E/AndroidRuntime(11975): at com.testing.ringer.RingerActivity.onCreate(RingerActivity.java:23) 11-09 15:41:09.909: E/AndroidRuntime(11975): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1072) 11-09 15:41:09.909: E/AndroidRuntime(11975): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1836) 11-09 15:41:09.909: E/AndroidRuntime(11975): ... 11 more </code></pre> <p>Ringer Manifest</p> <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt; &lt;manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.testing.ringer" android:versionCode="1" android:versionName="1.0" &gt; &lt;uses-sdk android:minSdkVersion="10" /&gt; &lt;uses-permission android:name="android.permission.RECORD_AUDIO"/&gt; &lt;application android:icon="@drawable/ic_launcher" android:label="@string/app_name" &gt; &lt;activity android:name=".RingerActivity" android:label="@string/app_name" &gt; &lt;intent-filter&gt; &lt;action android:name="android.intent.action.MAIN" /&gt; &lt;category android:name="android.intent.category.LAUNCHER" /&gt; &lt;/intent-filter&gt; &lt;/activity&gt; &lt;/application&gt; &lt;/manifest&gt; </code></pre>
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    1. CODid you try debugging?
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      1. USrekire
    2. COIt would be great if you could share the log. I guess the issue willnot be there if you call the mp.start in a handler with some small delay
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    3. COI find that mp = new MediaPlayer(); is unnecessary ; MediaPlayer.create(RingerActivity.this, R.raw.alarm); returns the media player object anyways.
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      1. USTushar Vengurlekar
 

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