无法更改Android上第二个活动的TextView中的文本

Question

我正在尝试制作android应用程序。它有两个活动：MainActivity和Activity_Service。在MainActivity中，有一个按钮“service”用于传递给Activity_Service。我想从MainActivity发送一个字符串到Activity_Service，然后在textview中显示它。我想向你展示代码。在MainActivity 创建意图：

service.setOnClickListener(new View.OnClickListener() { 

      @Override 
      public void onClick(View v) { 
       // TODO Auto-generated method stub 
       String message = "bla bla bla"; 
       Intent intent = new Intent(MainActivity.this, ActivityService.class); 
       intent.putExtra("message", message); 
       startActivity(intent); 

      } 
     }); 

而在Activity_Service onCreate（）方法：

public class ActivityService extends ActionBarActivity { 

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

    if (savedInstanceState == null) { 
     getSupportFragmentManager().beginTransaction() 
       .add(R.id.container, new PlaceholderFragment()).commit(); 
    } 
    Bundle bundle = getIntent().getExtras(); 
    String message = bundle.getString("message"); 
    System.out.println(message); 
    //TextView txtView = new TextView(this); 
    TextView txtView = (TextView)findViewById(R.id.name); 
    txtView.setText(message); 
} 

@Override 
public boolean onCreateOptionsMenu(Menu menu) { 

    // Inflate the menu; this adds items to the action bar if it is present. 
    getMenuInflater().inflate(R.menu.activity, 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(); 
    if (id == R.id.action_settings) { 
     return true; 
    } 
    return super.onOptionsItemSelected(item); 
} 

/** 
* A placeholder fragment containing a simple view. 
*/ 
public static class PlaceholderFragment extends Fragment { 

    public PlaceholderFragment() { 
    } 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
      Bundle savedInstanceState) { 
     View rootView = inflater.inflate(R.layout.fragment_activity, 
       container, false); 
     return rootView; 
    } 
} 

}

的XML文件，同时创造新的活动由Eclipse中创建（Activity_Service） ： activity_service.xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" 
xmlns:tools="http://schemas.android.com/tools" 
android:id="@+id/container" 
android:layout_width="match_parent" 
android:layout_height="match_parent" 
tools:context="com.example.alljoynandroid.ActivityService" 
tools:ignore="MergeRootFrame" /> 

Fragment_activity.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
xmlns:tools="http://schemas.android.com/tools" 
android:layout_width="match_parent" 
android:layout_height="match_parent" 
android:paddingBottom="@dimen/activity_vertical_margin" 
android:paddingLeft="@dimen/activity_horizontal_margin" 
android:paddingRight="@dimen/activity_horizontal_margin" 
android:paddingTop="@dimen/activity_vertical_margin" 
android:orientation="vertical" 
tools:context="com.example.alljoynandroid.ActivityService$PlaceholderFragment" > 

<TextView 
    android:id = "@+id/name" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" /> 

在的onCreate（）Activity_Service的方法，如果我用TextView txtView = new TextView(this);，它的工作原理：它可以从MainActivity传递到Activity_Service，但我们不能的setText。另一方面，如果我使用TextView txtView = (TextView)findViewById(R.id.name);，它不会全部工作。你能帮我解决吗？我正在尝试2天，现在我不知道。

Answer 1

删除此代码部分从Activity

if (savedInstanceState == null) { 
    getSupportFragmentManager().beginTransaction() 
      .add(R.id.container, new PlaceholderFragment()).commit(); 
} 

，改变

setContentView(R.layout.activity_service); 

到

setContentView(R.layout.fragment_activity);