Android Error [Attempt to invoke virtual method 'void android.app.ActionBar' on a null object reference]

Question

I have a code module which implements viewpager with navigation drawer, however, when I run the code I get the following error

01-26 09:20:02.958: D/AndroidR         


        

Answer 1

Your code is throwing on com.example.tabwithslidingdrawer.MainActivity.onCreate(MainActivity.java:95):

        // enabling action bar app icon and behaving it as toggle button
        getActionBar().setDisplayHomeAsUpEnabled(true);
        getActionBar().setHomeButtonEnabled(true);

The problem is pretty simple- your Activity is inheriting from the new android.support.v7.app.ActionBarActivity. You should be using a call to getSupportActionBar() instead of getActionBar().

If you look above around line 65 of your code you'll see that you're already doing that:

        actionBar = getSupportActionBar();
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_LIST);
        // TODO: Remove the redundant calls to getSupportActionBar()
        //       and use variable actionBar instead
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        getSupportActionBar().setHomeButtonEnabled(true);

And then lower down around line 87 it looks like you figured out the same:

        getSupportActionBar().setTitle(
                        Html.fromHtml("" + mTitle + " - "
                                        + menutitles[0] + ""));
        // getActionBar().setTitle(mTitle +menutitles[0]);

Notice how you commented out getActionBar().