android中开启actionbar的两种方法

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="com.baidu.homer"
     android:versionCode="1"
     android:versionName="1.0">
  <uses-sdk android:minSdkVersion="18"/>
  <application android:label="@string/app_name" android:icon="@drawable/ic_launcher"
      android:theme="@android:style/Theme.Holo">
    <activity android:name="MyActivity"
         android:label="@string/app_name">
      <intent-filter>
        <action android:name="android.intent.action.MAIN"/>
        <category android:name="android.intent.category.LAUNCHER"/>
      </intent-filter>
    </activity>
  </application>
</manifest>

import android.app.ActionBar;
import android.app.Activity;
import android.drm.DrmStore;
import android.os.Bundle;

public class MyActivity extends Activity {
  /**
   * Called when the activity is first created.
   */
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    ActionBar actionBar = getActionBar();
    actionBar.show();
  }
}