NullPointerException: Attempt to invoke virtual method 'void android.support.v7.app.ActionBar

Question

There are a number of questions dealing with this error. The solutions to these are:
- have the MainActivity class extend AppCompatActivity
- call getSupportActionBar(), not getActionBar()

I am already doing these.

I see a difference in appcompat-v7 22.1.1 and appcompat-v7 23.1.1. I get the error in 23. In 22 it works fine.

Stepping through the code in the debugger, I see that in AppCompatDelegateImplV7.intWindowDecorActionBar(), mHasActionBar is false, causing mActionBar to not be instantiated.

Stepping through the code in 22.1.1, the code is slightly different, but ultimately, I see that mHasActionBar is true and so the code works.

How do I deal with this?

import android.support.v7.app.ActionBar;
...
public class MainActivity extends AppCompatActivity  implements ...

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    ...    
    ActionBar actionBar = getSupportActionBar();

    actionBar.setDisplayHomeAsUpEnabled(true);
    actionBar.setHomeAsUpIndicator(R.drawable.ic_drawer);
    ....
}

Eric Liu · Accepted Answer · 2015-11-17 20:19:50Z

You might want to try to apply the NoActionBar theme to the application in the manifest, and use a Toolbar instead of Actionbar in the layout xml files.

Theme.AppCompat.Light.NoActionBar

Adding the Tool bar to the layout xml file

    <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar_player"
            android:layout_width="match_parent"
            android:layout_height="?android:attr/actionBarSize"
            style="@style/Topeka.TextAppearance.Title"
            android:background="@color/topeka_primary"
            android:elevation="@dimen/elevation_header">

Then in Java code, set it up as the Actionbar

 private void setUpToolbar(Player player) {
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar_player);
    setSupportActionBar(toolbar);
    getSupportActionBar().setDisplayShowTitleEnabled(false);
    ((TextView) toolbar.findViewById(R.id.title)).setText(getDisplayName(player));
}

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