导航抽屉中的打开活动

Question

每次我从导航抽屉中打开活动时，都会出现空白屏幕。我想从我的导航打开一个片段：

public class MainActivity extends ActionBarActivity { 

    private ListView mDrawerList; 
    private DrawerLayout mDrawerLayout; 
    private ArrayAdapter<String> mAdapter; 
    private ActionBarDrawerToggle mDrawerToggle; 
    private String mActivityTitle; 

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

     mDrawerList = (ListView)findViewById(R.id.navList);mDrawerLayout = (DrawerLayout)findViewById(R.id.drawer_layout); 
     mActivityTitle = getTitle().toString(); 

     addDrawerItems(); 
     setupDrawer(); 

     getSupportActionBar().setDisplayHomeAsUpEnabled(true); 
     getSupportActionBar().setHomeButtonEnabled(true); 
    } 

    private void addDrawerItems() { 
     String[] osArray = {"Math", "Physics", "Chemistry"}; 
     mAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, osArray); 
     mDrawerList.setAdapter(mAdapter); 

     mDrawerList.setOnItemClickListener(new AdapterView.OnItemClickListener() { 

      @Override 
      public void onItemClick(AdapterView<?> parent, View view, int position, long id) { 

        switch(position) { 
         case 0: 
          Intent a = new Intent(MainActivity.this, MathActivity.class); 
          startActivity(a); 
          break; 

         case 1: 
          Intent b = new Intent(MainActivity.this, PhysicsActivity.class); 
          startActivity(b); 
          break; 
         case 2: 
          Intent c = new Intent(MainActivity.this, ChemistryActivity.class); 
          startActivity(c); 
          break; 
         default: 
        } 

      } 

     }); 


    } 
    private void setupDrawer() { 
     mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout, R.string.drawer_open, R.string.drawer_close) { 

      /** Called when a drawer has settled in a completely open state. */ 
      public void onDrawerOpened(View drawerView) { 
       super.onDrawerOpened(drawerView); 
       getSupportActionBar().setTitle("Navigation!"); 
       invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu() 
      } 

      /** Called when a drawer has settled in a completely closed state. */ 
      public void onDrawerClosed(View view) { 
       super.onDrawerClosed(view); 
       getSupportActionBar().setTitle(mActivityTitle); 
       invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu() 
      } 
     }; 

     mDrawerToggle.setDrawerIndicatorEnabled(true); 
     mDrawerLayout.setDrawerListener(mDrawerToggle); 
    } 

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

    @Override 
    public void onConfigurationChanged(Configuration newConfig) { 
     super.onConfigurationChanged(newConfig); 
     mDrawerToggle.onConfigurationChanged(newConfig); 
    } 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     // Inflate the menu; this adds items to the action bar if it is present. 
     getMenuInflater().inflate(R.menu.menu_main, menu); 
     return true; 
    } 

    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 
     // Handle action bar item clicks here. The action bar will 
     // automatically handle clicks on the Home/Up button, so long 
     // as you specify a parent activity in AndroidManifest.xml. 
     int id = item.getItemId(); 

     //noinspection SimplifiableIfStatement 
     if (id == R.id.action_settings) { 
      return true; 
     } 

     // Activate the navigation drawer toggle 
     if (mDrawerToggle.onOptionsItemSelected(item)) { 
      return true; 
     } 

     return super.onOptionsItemSelected(item); 
    } 
} 

要打开活动是这样的：

public class MathActivity extends Activity{ 

protected void onCreate(Bundle bundle) { 

    setContentView(R.layout.math_fragment_activity); 
    super.onCreate(bundle); 
} 

} 

每次我这样做，出现空白屏幕。为什么会发生这种情况，谁能帮我解决这个问题？

UPDATE： 这是我的布局文件：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
      android:layout_width="match_parent" 
      android:layout_height="match_parent" 
      android:orientation="vertical" > 

<ListView 
    android:id="@+id/listViewAnimals" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
    android:dividerHeight="0.1dp" 
    android:divider="#0000CC"/> </RelativeLayout> 

Answer 1

尝试切换您的setContentiew是super.onCreate调用之后。