Android: NullPointerException at getActionBar

Question

I'm implementing navigation drawer sliding menu .getting java.lang.NullPointerException at the

getActionBar().setDisplayShowHomeEnabled(true);
getActionBar().setHomeButtonEnabled(true);

In my Application I have tried activity extended Activity and also AppCompatActivity.

Here is my onCreate code

protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        mTitle = mDrawerTitle = getTitle();

        navMenuTitles = getResources().getStringArray(R.array.nav_drawer_items);
        navMenuIcons = getResources().obtainTypedArray(R.array.nav_drawer_icons);
        mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
        mDrawerList = (ListView) findViewById(R.id.list_slidermenu);
        navDrawerItems = new ArrayList<NavDrawerItem>();
        navDrawerItems.add(new NavDrawerItem(navMenuTitles[0], navMenuIcons.getResourceId(0, -1)));
        navDrawerItems.add(new NavDrawerItem(navMenuTitles[1], navMenuIcons.getResourceId(1, -1)));
        navDrawerItems.add(new NavDrawerItem(navMenuTitles[2], navMenuIcons.getResourceId(2, -1)));
        navDrawerItems.add(new NavDrawerItem(navMenuTitles[3], navMenuIcons.getResourceId(3, -1), true, "22"));
        navDrawerItems.add(new NavDrawerItem(navMenuTitles[4], navMenuIcons.getResourceId(4, -1)));
        navDrawerItems.add(new NavDrawerItem(navMenuTitles[5], navMenuIcons.getResourceId(5, -1), true, "50+"));
        navMenuIcons.recycle();
        mDrawerList.setOnItemClickListener(new SlideMenuClickListener());
        adapter = new NavDrawerListAdapter(getApplicationContext(), navDrawerItems);
        mDrawerList.setAdapter(adapter);
       //abling action bar app icon and behaving it as toggle button
        getActionBar().setDisplayShowHomeEnabled(true);
        getActionBar().setHomeButtonEnabled(true);
        mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout,

                R.drawable.menu_left, //nav menu toggle icon
                R.string.app_name, // nav drawer open - description for accessibility
                R.string.app_name // nav drawer close - description for accessibility
        )
        {
            public void onDrawerClosed(View view) {
                getActionBar().setTitle(mTitle);
                // calling onPrepareOptionsMenu() to show action bar icons
                invalidateOptionsMenu();
            }

            public void onDrawerOpened(View drawerView) {
                getActionBar().setTitle(mDrawerTitle);
                // calling onPrepareOptionsMenu() to hide action bar icons
                invalidateOptionsMenu();}
        };

        mDrawerLayout.setDrawerListener(mDrawerToggle);
        if (savedInstanceState == null) {
            // on first time display view for first nav item
            displayView(0);
        }
    }

Here is LogCat inforamtion

 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.tazeen.slidingmenu/com.example.tazeen.slidingmenu.MainActivity}: java.lang.NullPointerException
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
            at android.app.ActivityThread.access$600(ActivityThread.java:130)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:4745)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at com.example.tazeen.slidingmenu.MainActivity.onCreate(MainActivity.java:62)
            at android.app.Activity.performCreate(Activity.java:5008)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
            at android.app.ActivityThread.access$600(ActivityThread.java:130)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:4745)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
            at dalvik.system.NativeStart.main(Native Method)

Answer 1

If you are extending from AppCompatActivity you should use, getSupportActionBar()

If you are extending form Activity, You can use getActionBar(),

But in both the cases,

You have make sure to have a ActionBar supported theme assigned for your Activity.

Eg: Theme.AppCompat.Light

or you can programatically do it,

requestWindowFeature(Window.FEATURE_ACTION_BAR);

before

super.onCreate(savedInstanceState);

But it is best to have a style declared and assigned for your activity rather than doing it programatically.

Answer 2

extends simple Activity instead of ActionBarActivity.and please always check null before setDisplayShowHomeEnabled() like:

if(getActionBar()!=null){
    getActionBar().setDisplayShowHomeEnabled(true);
        getActionBar().setHomeButtonEnabled(true);
    }

and another solution is to use getSupportActionBar() instead of getActionBar() and then

if(getSupportActionBar()!=null){
    getSupportActionBar().setDisplayShowHomeEnabled(true);
        getgetSupportActionBarActionBar().setHomeButtonEnabled(true);
    }

enjoy your code:)