Ящик навигации перекрывается фрагментами в Android

Я создал навигационный ящик в своем основном действии. Когда я нажимаю на элемент навигационного ящика, я запускаю фрагмент в своем основном действии. Если снова щелкнуть значок навигационного ящика, ящик перекрывается с фрагментом.

я хочу отделить фрагмент, когда я открываю навигационный ящик во второй раз.

Context mContext;
UIController mController;
private DrawerLayout mDrawerLayout;
private ListView mDrawerList;
private ActionBarDrawerToggle mDrawerToggle;

private CharSequence mTitle;
private String[] mPlanetTitles = { "Photos", "Videos", "Settings" };

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    mTitle = "test";

    mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
    mDrawerList = (ListView) findViewById(R.id.left_drawer);

    // Set the adapter for the list view
    mDrawerList.setAdapter(new ArrayAdapter<String>(this,
            R.layout.drawer_list_item, mPlanetTitles));
    // Set the list's click listener
    mDrawerList.setOnItemClickListener(new DrawerItemClickListener());

    mDrawerToggle = new ActionBarDrawerToggle(this, /* host Activity */
    mDrawerLayout, /* DrawerLayout object */
    R.drawable.ic_drawer, /*
                                         * nav drawer icon to replace 'Up'
                                         * caret
                                         */
    R.string.drawer_open, /* "open drawer" description */
    R.string.drawer_close /* "close drawer" description */
    ) {

        /** Called when a drawer has settled in a completely closed state. */
        public void onDrawerClosed(View view) {
            getActionBar().setTitle(mTitle);
        }

        /** Called when a drawer has settled in a completely open state. */
        public void onDrawerOpened(View drawerView) {
            getActionBar().setTitle(mTitle);
        }
    };

    // Set the drawer toggle as the DrawerListener
    mDrawerLayout.setDrawerListener(mDrawerToggle);

    getActionBar().setDisplayHomeAsUpEnabled(true);
    getActionBar().setHomeButtonEnabled(true);

}

@Override
protected void onDestroy() {
    super.onDestroy();
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Pass the event to ActionBarDrawerToggle, if it returns
    // true, then it has handled the app icon touch event
    if (mDrawerToggle.onOptionsItemSelected(item)) {
        return true;
    }
    // Handle your other action bar items...

    return super.onOptionsItemSelected(item);
}

@Override
protected void onPostCreate(Bundle savedInstanceState) {
    super.onPostCreate(savedInstanceState);
    // Sync the toggle state after onRestoreInstanceState has occurred.
    mDrawerToggle.syncState();
}

private class DrawerItemClickListener implements
        ListView.OnItemClickListener {
    @Override
    public void onItemClick(AdapterView parent, View view, int position,
            long id) {
        selectItem(position);
        mDrawerLayout.closeDrawer(mDrawerList);

    }
}

public void selectItem(int position) {
    switch (position) {
    case 0:
        getFragmentManager()
                .beginTransaction()
                .replace(android.R.id.content,
                        AlbumListFragment.newInstance()).commit();
        break;
    }
}