Google android

package ua.com.cls;
 
import android.annotation.SuppressLint;
import android.app.Activity;
import android.app.FragmentManager;
import android.content.res.Configuration;
import android.os.Bundle;
import android.support.v4.app.ActionBarDrawerToggle;
import android.support.v4.app.Fragment;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
 
import java.util.Locale;
 
public class MainActivity extends Activity {
    
    private DrawerLayout  mDrawerLayout;
    private ListView mDrawerList;
    private ActionBarDrawerToggle mDrawerToggle;
    
    private CharSequence mTitleDrawer;
    private CharSequence mTitle;
    private String[] mTitleDrawerString;
 
    @SuppressLint("NewApi")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);      
        mTitleDrawer = mTitle = getTitle();     
        mTitleDrawerString = getResources().getStringArray(R.array.dawer_list);     
        mDrawerLayout = (DrawerLayout) this.findViewById(R.id.drawer_layout);
        mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START);
        mDrawerList = (ListView) this.findViewById(R.id.drawe_list_view);
        mDrawerList.setAdapter(new ArrayAdapter<String>(
            this,  R.layout.drawer_list_item,
            mTitleDrawerString)); 
        mDrawerList.setOnClickListener((OnClickListener) new DrawerClickListener());
/* 
getActionBar() возвращает null
*/
        getActionBar().setDisplayHomeAsUpEnabled(true);
        getActionBar().setHomeButtonEnabled(true);
    
        mDrawerToggle = new ActionBarDrawerToggle(
                this,                 
                mDrawerLayout,         
                R.drawable.ic_drawer,  
                R.string.drawer_open,  
                R.string.drawer_close){
            public void onDrawerClosed(View view) {
                getActionBar().setTitle(mTitle);
                invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
            }
 
            public void onDrawerOpened(View drawerView) {
                getActionBar().setTitle(mTitleDrawer);
                invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
            }           
        };
        mDrawerLayout.setDrawerListener(mDrawerToggle);
        if (savedInstanceState == null) {
        }
    }   
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.menu, menu);
        return super.onCreateOptionsMenu(menu);
    }
    
    private class DrawerClickListener implements ListView.OnItemClickListener{
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position,
                long id) {
        android.app.Fragment fragment = new MainFragment();
        FragmentManager fragmentManager = getFragmentManager();
        fragmentManager.beginTransaction().replace(R.id.content_frame, fragment).commit();
        }           
    }   
}