title: How can I get ActionBar from Main(ActionBarActivity) intent Activity
body: <p>I use ActionBarActivity intent a new Activity
  but I cant call ActionBar method in Activity</p>
  
  <pre><code>//        requestWindowFeature(Window.FEATURE_ACTION_BAR);
  //        getActionBar().setTitle("123");
          ActionBar actionBar =getActionBar();
  //
          actionBar.setDisplayHomeAsUpEnabled(true);
  </code></pre>
  
  <p>will get null</p>
  
  <pre><code>01-14 16:29:58.712    3405-3405/com.fragment.test E/AndroidRuntime﹕ FATAL EXCEPTION: main
      Process: com.fragment.test, PID: 3405
      java.lang.RuntimeException: Unable to start activity ComponentInfo{com.fragment.test/com.fragment.test.Ac1}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setDisplayHomeAsUpEnabled(boolean)' on a null object reference
              at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
              at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
              at android.app.ActivityThread.access$800(ActivityThread.java:144)
              at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
              at android.os.Handler.dispatchMessage(Handler.java:102)
              at android.os.Looper.loop(Looper.java:135)
              at android.app.ActivityThread.main(ActivityThread.java:5221)
              at java.lang.reflect.Method.invoke(Native Method)
              at java.lang.reflect.Method.invoke(Method.java:372)
              at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
              at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
       Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setDisplayHomeAsUpEnabled(boolean)' on a null object reference
              at com.fragment.test.Ac1.onCreate(Ac1.java:15)
              at android.app.Activity.performCreate(Activity.java:5933)
              at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
              at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
              at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
              at android.app.ActivityThread.access$800(ActivityThread.java:144)
              at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
              at android.os.Handler.dispatchMessage(Handler.java:102)
              at android.os.Looper.loop(Looper.java:135)
              at android.app.ActivityThread.main(ActivityThread.java:5221)
              at java.lang.reflect.Method.invoke(Native Method)
              at java.lang.reflect.Method.invoke(Method.java:372)
              at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
              at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
  01-14 16:30:01.233    3405-3405/com.fragment.test I/Process﹕ Sending signal. PID: 3405 SIG: 9
  01-14 17:12:11.968    3795-3795/com.fragment.test I/Process﹕ Sending signal. PID: 3795 SIG: 9
  </code></pre>
  
  <p>Can I get ActionBar without change the Activity to ActionBarActivity
  thanks</p>