[android] getSupportActionBar() The method getSupportActionBar() is undefined for the type TaskActivity. Why?

I was recommended to extend my Activity class from ActionBarActivity

Here is the previous code:

import android.support.v7.app.ActionBar;
import android.support.v7.app.ActionBarActivity;  

public class MainActivity extends Activity  {

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

I wrote new application and followed advice.

import android.os.Bundle;
    import android.support.v7.app.ActionBar;
    import android.support.v7.app.ActionBarActivity;            

    public class MainActivity extends ActionBarActivity {

          @Override
          public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            ActionBar actionBar =getSupportActionBar();
            actionBar.setDisplayHomeAsUpEnabled(true);            
            setContentView(R.layout.activity_main);
          }

          @Override
          public boolean onCreateOptionsMenu(Menu menu) {
            getMenuInflater().inflate(R.menu.main, menu);
            return true;
          }            
        }

If I use ACtionBarActivity instead of Activity, I get the following error on the phone, when I try to run it:

The method getSupportActionBar() is undefined for the type TaskActivity

Here is another solution you could have used. It is working in my app.

      @Override
      public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        android.support.v7.app.ActionBar actionBar =getSupportActionBar();
        actionBar.setDisplayHomeAsUpEnabled(true);            
        setContentView(R.layout.activity_main)

Then you can get rid of that import for the one line ActionBar use.

If you are extending from an AppCompatActivity and are trying to get the ActionBar from the Fragment, you can do this:

ActionBar mActionBar = ((AppCompatActivity) getActivity()).getSupportActionBar();

You have to change the extends Activity to extends AppCompactActivity then try set and getSupportActionBar()

If you are already extending from ActionBarActivity and you are trying to get the action bar from a fragment:

ActionBar mActionBar = (ActionBarActivity)getActivity()).getSupportActionBar();

Can you set the ActionBar before you set the Contient View? This order would be better:

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

    ActionBar actionBar =getSupportActionBar();
    actionBar.setDisplayHomeAsUpEnabled(true);            
  }

Your class needs to extend from ActionBarActivity, rather than a plain Activity in order to use the getSupport*() methods.

Update [2015/04/23]: With the release of Android Support Library 22.1, you should now extend AppCompatActivity. Also, you no longer have to extend ActionBarActivity or AppCompatActivity, as you can now incorporate an AppCompatDelegate instance in any activity.