android.app.Actionbar.setHomeButtonEnabled returns null

Question

I am trying to create swipeable tabs in android. Before even activity starts application crashessaying that setHomeButtonenabled returning nullpointerexception.

My onCreate method:

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

    // Initilization
    viewPager = (ViewPager) findViewById(R.id.pager);
    actionBar = getActionBar();
    mAdapter = new TabsPagerAdapter(getSupportFragmentManager());

    viewPager.setAdapter(mAdapter);
    actionBar.setHomeButtonEnabled(false);
    actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);        

    // Adding Tabs
    for (String tab_name : tabs) {
        actionBar.addTab(actionBar.newTab().setText(tab_name)
                .setTabListener(this));
    }

    /**
     * on swiping the viewpager make respective tab selected
     * */
    viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {

        @Override
        public void onPageSelected(int position) {
            // on changing the page
            // make respected tab selected
            actionBar.setSelectedNavigationItem(position);
        }

        @Override
        public void onPageScrolled(int arg0, float arg1, int arg2) {
        }

        @Override
        public void onPageScrollStateChanged(int arg0) {
        }
    });


}

Here is my LOGCAT:

    03-09 22:38:24.674: E/AndroidRuntime(1297): FATAL EXCEPTION: main
03-09 22:38:24.674: E/AndroidRuntime(1297): Process: com.appquest.prodactivity, PID: 1297
03-09 22:38:24.674: E/AndroidRuntime(1297): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.appquest.prodactivity/com.appquest.prodactivity.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setHomeButtonEnabled(boolean)' on a null object reference
03-09 22:38:24.674: E/AndroidRuntime(1297):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
03-09 22:38:24.674: E/AndroidRuntime(1297):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
03-09 22:38:24.674: E/AndroidRuntime(1297):     at android.app.ActivityThread.access$800(ActivityThread.java:144)
03-09 22:38:24.674: E/AndroidRuntime(1297):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
03-09 22:38:24.674: E/AndroidRuntime(1297):     at android.os.Handler.dispatchMessage(Handler.java:102)
03-09 22:38:24.674: E/AndroidRuntime(1297):     at android.os.Looper.loop(Looper.java:135)
03-09 22:38:24.674: E/AndroidRuntime(1297):     at android.app.ActivityThread.main(ActivityThread.java:5221)
03-09 22:38:24.674: E/AndroidRuntime(1297):     at java.lang.reflect.Method.invoke(Native Method)
03-09 22:38:24.674: E/AndroidRuntime(1297):     at java.lang.reflect.Method.invoke(Method.java:372)
03-09 22:38:24.674: E/AndroidRuntime(1297):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
03-09 22:38:24.674: E/AndroidRuntime(1297):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
03-09 22:38:24.674: E/AndroidRuntime(1297): Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setHomeButtonEnabled(boolean)' on a null object reference
03-09 22:38:24.674: E/AndroidRuntime(1297):     at com.appquest.prodactivity.MainActivity.onCreate(MainActivity.java:31)
03-09 22:38:24.674: E/AndroidRuntime(1297):     at android.app.Activity.performCreate(Activity.java:5933)
03-09 22:38:24.674: E/AndroidRuntime(1297):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
03-09 22:38:24.674: E/AndroidRuntime(1297):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)

I am using minimumsdk=14 and target=21

Instead of FragmentActivity use AppCompatActivity – Mohan Prasath Dec 18 '16 at 13:29 — Mohan Prasath, Dec 18 '16 at 13:29

score 2 · Accepted Answer · answered Mar 09 '15 at 17:18

2

If your activity extends ActionBarActivity then change

actionBar = getActionBar();

to

actionBar = getSupportedActionBar();

answered Mar 09 '15 at 17:18

Pooja

2,417
20
39

my activity extends to FragmentActivity and implements ActionBar.TabListener – Harshil Pansare Mar 09 '15 at 17:21
@Harsh Do not use `ActionBar.TabListener`, that is deprecated. – Jared Burrows Mar 09 '15 at 17:21
Yes, I know. Is there any other simple way of creating tabs? – Harshil Pansare Mar 09 '15 at 17:24
@Pooja if he is using minSdk of 14, he most likely is not using AppCompat. – Jared Burrows Mar 09 '15 at 17:26
@Harsh Yes but not a good idea. Please see my answer here: http://stackoverflow.com/a/26563111/950427. – Jared Burrows Mar 09 '15 at 17:27
@Jared Burrows I am working on app which has minSDK 14 and I am using AppCompat. – Pooja Mar 09 '15 at 17:27
@Pooja That's great? Reread what I just said. He already said he was using a `FragmentActivity` no `ActionBarActivity`. – Jared Burrows Mar 09 '15 at 17:29
@Jared Burrows - Your answer looks interesting. I'll give it a try. Thank you. :) – Harshil Pansare Mar 09 '15 at 17:30
@Harsh I highly suggest using AppCompat for Material Design. – Jared Burrows Mar 09 '15 at 17:30
actually I am using appcompat_v7 – Harshil Pansare Mar 09 '15 at 17:30
@Jared Yes I got it that's I didn't comment further. And read my answer carefully I wrote that use my ans only if extends ActionBarActivity. – Pooja Mar 09 '15 at 17:31
@Pooja Yes, you answer is right but only if he was using `ActionBarActivity` from the AppCompat support lib(which I hope he is). – Jared Burrows Mar 09 '15 at 18:17
Yes @jared. And I have clearly mentioned that in very first sentence of my answer. – Pooja Mar 09 '15 at 18:19

score 0 · Answer 2 · answered Jun 01 '16 at 09:47

0

**change in AndroidManifest file theme to @android:style/Theme.Holo.Light

answered Jun 01 '16 at 09:47

Nagashree

105
1
5

score 0 · Answer 3 · answered Aug 28 '18 at 05:57

0

change the theme for your activity like this android:theme="@android:style/Theme.Holo.Light.DialogWhenLarge"

it is worked for me.

answered Aug 28 '18 at 05:57

Balaji Bal

60
3

android.app.Actionbar.setHomeButtonEnabled returns null

3 Answers3