先從onActivityResult

Question

第一個活動我想打開兩個其他活動，然後我想在活動A.on活動一個我打開活動乙還有我打開活動從活動C均扮演選定的歌曲C。 我想播放精選歌曲活動C。

但我不明白。怎麼了？ 非常感謝，Vinzenz :)

---

這是ActivityA：

LinearLayoutBrowse.setOnClickListener(new View.OnClickListener() { 
    @Override 
    public void onClick(View arg0) { 
    Intent i = new Intent(getApplicationContext(), BrowseActivity.class); 
     startActivityForResult(i, 100); 

      final Handler handler = new Handler(); 
      handler.postDelayed(new Runnable() { 
       @Override 
       public void run() { 
        mDrawerLayout.closeDrawers(); 
       } 
      }, 300); 

     } 
    }); 

@Override 
protected void onActivityResult(int requestCode, 
           int resultCode, Intent data) { 

    super.onActivityResult(requestCode, resultCode, data); 
    if(resultCode == 100){ 
     currentSongIndex = data.getExtras().getInt("songIndex"); 

     //drawerclose 


     // play selected song 
     playSong(currentSongIndex); 

    } 

} 

---

這是ActivityB：

 LinearLayoutTitel.setOnClickListener(new View.OnClickListener() { 

     @Override 
     public void onClick(View arg0) { 
      myViewFlipper.showPrevious(); 
      Intent i = new Intent(BrowseActivity.this, AllSongs.class); 
      startActivityForResult(i, 100); 

     } 
    }); 


} 
@Override 
protected void onActivityResult(int requestCode, int resultCode, Intent data) { 
    // this is the data that comes back from Activity C when Activity C calls finish() 

    // set the data as the result 
    setResult(???); 

    // then you can finish 
    finish(); 
} 

---

這是ActivityC：

lv.setOnItemClickListener(new OnItemClickListener() { 

     @Override 
     public void onItemClick(AdapterView<?> parent, View view, 
       int position, long id) { 
      // getting listitem index 
      int songIndex = position; 

      // Starting new intent 
      Intent in = new Intent(getApplicationContext(), 
        MainActivity.class); 


      // Sending songIndex to BrowseActivity 
      in.putExtra("songIndex", songIndex); 

      setResult(100, in); 
      // Closing PlayListView 
      finish(); 
     } 

Answer 1

在您的第三個Activity中，構造函數Intent應爲空。取而代之的

Intent in = new Intent(getApplicationContext(), MainActivity.class); 

應該

Intent in = new Intent(); 

否則，您創建的MainActivity一個新的實例，它會調用其onCreate()。