NullPointerException error in android activity

Question

Getting this error even though have added all the activities in manifest. What to do?

11-23 15:37:55.465 24625-24625/com.aaa.fyp E/AndroidRuntime: FATAL EXCEPTION: main
11-23 15:37:55.465 24625-24625/com.aaa.fyp E/AndroidRuntime: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.aaa.fyp/com.slidingmenu_tabhostviewpager.MainActivity}: java.lang.NullPointerException
11-23 15:37:55.465 24625-24625/com.aaa.fyp E/AndroidRuntime:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2372)
11-23 15:37:55.465 24625-24625/com.aaa.fyp E/AndroidRuntime:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2424)
11-23 15:37:55.465 24625-24625/com.aaa.fyp E/AndroidRuntime:     at android.app.ActivityThread.access$600(ActivityThread.java:169)
11-23 15:37:55.465 24625-24625/com.aaa.fyp E/AndroidRuntime:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1388)
11-23 15:37:55.465 24625-24625/com.aaa.fyp E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:107)
11-23 15:37:55.465 24625-24625/com.aaa.fyp E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:194)
11-23 15:37:55.465 24625-24625/com.aaa.fyp E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:5433)
11-23 15:37:55.465 24625-24625/com.aaa.fyp E/AndroidRuntime:     at java.lang.reflect.Method.invokeNative(Native Method)
11-23 15:37:55.465 24625-24625/com.aaa.fyp E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Method.java:525)
11-23 15:37:55.465 24625-24625/com.aaa.fyp E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:924)
11-23 15:37:55.465 24625-24625/com.aaa.fyp E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:691)
11-23 15:37:55.465 24625-24625/com.aaa.fyp E/AndroidRuntime:     at dalvik.system.NativeStart.main(Native Method)
11-23 15:37:55.465 24625-24625/com.aaa.fyp E/AndroidRuntime:  Caused by: java.lang.NullPointerException
11-23 15:37:55.465 24625-24625/com.aaa.fyp E/AndroidRuntime:     at com.slidingmenu_tabhostviewpager.MainActivity.onCreate(MainActivity.java:43)
11-23 15:37:55.465 24625-24625/com.aaa.fyp E/AndroidRuntime:     at android.app.Activity.performCreate(Activity.java:5179)
11-23 15:37:55.465 24625-24625/com.aaa.fyp E/AndroidRuntime:     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1146)
11-23 15:37:55.465 24625-24625/com.aaa.fyp E/AndroidRuntime:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2336)
11-23 15:37:55.465 24625-24625/com.aaa.fyp E/AndroidRuntime:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2424) 
11-23 15:37:55.465 24625-24625/com.aaa.fyp E/AndroidRuntime:     at android.app.ActivityThread.access$600(ActivityThread.java:169) 
11-23 15:37:55.465 24625-24625/com.aaa.fyp E/AndroidRuntime:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1388) 
11-23 15:37:55.465 24625-24625/com.aaa.fyp E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:107) 
11-23 15:37:55.465 24625-24625/com.aaa.fyp E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:194) 
11-23 15:37:55.465 24625-24625/com.aaa.fyp E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:5433) 
11-23 15:37:55.465 24625-24625/com.aaa.fyp E/AndroidRuntime:     at java.lang.reflect.Method.invokeNative(Native Method) 
11-23 15:37:55.465 24625-24625/com.aaa.fyp E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Method.java:525)

This is the class i have set as launcher activity:

public class MainActivity extends ActionBarActivity {

    DrawerLayout drawerLayout;
    RelativeLayout drawerPane;
    ListView lvNav;

    List<NavItem> listNavItems;
    List<Fragment> listFragments;

    ActionBarDrawerToggle actionBarDrawerToggle;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        getSupportActionBar().setDisplayHomeAsUpEnabled(true);

        drawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
}

Line 43 is:

 getSupportActionBar().setDisplayHomeAsUpEnabled(true);

Manifest:

   <activity
        android:name="com.slidingmenu_tabhostviewpager.MainActivity"
        android:label="@string/app_name"
        android:theme="@style/AppTheme.NoActionBar" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

your problem is `android:theme="@style/AppTheme.NoActionBar"` — M D, Nov 23 '15 at 10:46
Oh. But all my other activities had that written as well. and they worked. Anyways thanks :) — AAA, Nov 23 '15 at 10:48
the problemm is that since you are using a `NoActionBar` `Theme` you should then setup a `android.support.v7.widget.Toolbar` and then do `setSupportActionBar(toolbar);` and then you can do your code. — Kostas Drak, Nov 23 '15 at 10:55

NullPointerException error in android activity

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