Android activity stopped unexpectedly

Question

I am trying to use SharedPreference to store some values and access them later, but don't know why my Activity crashed and giving me this error.

06-12 11:03:40.459    1525-1525/? E/AndroidRuntime﹕ FATAL EXCEPTION: main
    java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.ets.medecord/com.ets.medecord.SplashActivity}: java.lang.NullPointerException
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1680)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1784)
            at android.app.ActivityThread.access$1500(ActivityThread.java:123)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:939)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:130)
            at android.app.ActivityThread.main(ActivityThread.java:3835)
            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:864)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:622)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at android.content.ContextWrapper.getPackageName(ContextWrapper.java:120)
            at android.preference.PreferenceManager.getDefaultSharedPreferencesName(PreferenceManager.java:353)
            at android.preference.PreferenceManager.getDefaultSharedPreferences(PreferenceManager.java:348)
            at com.ets.medecord.SplashActivity.<init>(SplashActivity.java:15)
            at java.lang.Class.newInstanceImpl(Native Method)
            at java.lang.Class.newInstance(Class.java:1409)
            at android.app.Instrumentation.newActivity(Instrumentation.java:1021)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1672)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1784)
            at android.app.ActivityThread.access$1500(ActivityThread.java:123)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:939)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:130)
            at android.app.ActivityThread.main(ActivityThread.java:3835)
            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:864)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:622)
            at dalvik.system.NativeStart.main(Native Method)

Code which I am using in my SplashActivity.java. when I run my app it crashes but if I remove those lines containing SharedPreference.

public class SplashActivity extends ActionBarActivity{
static final int PAUSE_TIME = 2000;
SharedPreferences pref = PreferenceManager.getDefaultSharedPreferences(this);
SharedPreferences.Editor editor = pref.edit();
boolean isAppFirstStart = pref.getBoolean("start",true);
Handler handler;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_splash);
    handler = new Handler();
    getSupportActionBar().hide();

    new Thread(new Runnable() {
        @Override
        public void run() {
            try {
                Thread.sleep(PAUSE_TIME);
            } catch(InterruptedException e) {
                e.printStackTrace();
            }
            handler.post(new Runnable() {
                @Override
                public void run() {
                    if(isAppFirstStart) {
                        editor.putBoolean("start",false);
                        editor.commit();
                        startActivity(new Intent(getApplicationContext(), IntroActivity.class));
                        finish();
                    } else {
                        startActivity(new Intent(getApplicationContext(), LoginActivity.class));
                        finish();
                    }
                }
            });
        }
    }).start();
  }
 }

Try putting those shared preference lines in your onCreate(). — hungryghost, Jun 12 '15 at 05:45
Moving those lines should fix your error. You'll have to make `pref` and `editor` final as they are used in an inner class. — Matter Cat, Jun 12 '15 at 05:49
@MatterCat but why android studio don't these as problem. cause whenever I use any other variable in inner class it suggest to make it final but this time it won't showing anything like that. — Vishvendra Singh, Jun 12 '15 at 05:52
I'm not sure what you're saying. You're saying that it's not asking you to make them final? I plugged your code into Android Studio and it shows squiggly little lines under `editor`, hence the "use final" suggestion. If you fixed it differently, though, what matters more if it works or not. Is it working now? — Matter Cat, Jun 12 '15 at 05:55

score 2 · Answer 1 · edited May 23 '17 at 11:58

2

Outside class methods and in static initialization blocks, this is null. It hasn't been initialized yet.

Thus, you can't pass this in such places.

Default constructor vs. inline field initialization

edited May 23 '17 at 11:58

Community

1
1

answered Jun 12 '15 at 05:54

frogatto

28,539
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hungryghost · Accepted Answer · 2015-06-12T17:49:07.053

The problem is with:

SharedPreferences pref = PreferenceManager.getDefaultSharedPreferences(this);

Move your shared preference lines to onCreate, like this:

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_splash);

    SharedPreferences pref = PreferenceManager.getDefaultSharedPreferences(this);
    SharedPreferences.Editor editor = pref.edit();
    ...
}

Then it will work.

The reason PreferenceManager.getDefaultSharedPreferences(this) was giving you a null pointer exception, is because this cannot be resolved before onCreate().

Android activity stopped unexpectedly

2 Answers2