如何等待onActivityResult完成？

问题描述：

我如果用户不同意蓝牙，它通过这段代码要求的激活不应该打开一个片段如何等待onActivityResult完成？

Intent mIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE); 
     mIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 240); 
      startActivityForResult(mIntent, 1); 
    //Here I want to exit the method in case result is denied 
getActivity().getSupportFragmentManager().beginTransaction().replace(R.id.content,new ServerFragment()).addToBackStack(null).commit();

我一直在寻找在相当多的地方，唯一的我发现的事情是使用新活动的setResult（在我的情况下，onActivityResult在调用活动中被覆盖，因为此代码在一个片段内）

任何想法？

谢谢！

编辑：这里有一个堆栈跟踪

java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=131073, result=240, data=null} to activity {bt.bt/bt.bt.MainActivity}: java.lang.IllegalStateException: Can not perform this action after onSaveInstanceState 
                       at android.app.ActivityThread.deliverResults(ActivityThread.java:3659) 
                       at android.app.ActivityThread.handleSendResult(ActivityThread.java:3702) 
                       at android.app.ActivityThread.access$1300(ActivityThread.java:155) 
                       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1366) 
                       at android.os.Handler.dispatchMessage(Handler.java:102) 
                       at android.os.Looper.loop(Looper.java:135) 
                       at android.app.ActivityThread.main(ActivityThread.java:5343) 
                       at java.lang.reflect.Method.invoke(Native Method) 
                       at java.lang.reflect.Method.invoke(Method.java:372) 
                       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:905) 
                       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:700) 
                      Caused by: java.lang.IllegalStateException: Can not perform this action after onSaveInstanceState

答

你应该只返回你的函数启动意图之后。然后等待onActivityResult中的回调。在这种方法中，如果结果是RESULT_OK，那么你会开始你的片段。

protected void onActivityResult(int requestCode, int resultCode, Intent data) { 
    if (requestCode == your_request_code_here) { 
     if (resultCode != Activity.RESULT_CANCELED) { 
      // start fragment 
     } 
    } 
}

全部活动：

public class MainActivity extends AppCompatActivity { 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); 
     setSupportActionBar(toolbar); 

     FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab); 
     fab.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View view) { 
       Intent mIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE); 
       mIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 240); 
       startActivityForResult(mIntent, 1); 
      } 
     }); 
    } 

    @Override 
    public void onPause() { 
     super.onPause(); 
    } 

    @Override 
    public void onResume() { 
     super.onResume(); 
    } 

    @Override 
    protected void onActivityResult(int requestCode, int resultCode, Intent data) { 
     if (requestCode == 1) { 
      if (resultCode != Activity.RESULT_CANCELED) { 

      } 
     } 
    } 
}

这是行不通的，因为onActivityResult是异步的，这意味着调用片段不会等待结果，它会继续执行。如果我尝试从onActivityResult向屏幕添加新片段，则会生成IllegalStateException。 – Stefan

请发布您的代码和堆栈跟踪。这是处理这些请求的标准方式。 – Francesc

发表了它，看一看 – Stefan

答

正如你所粘贴代码，您只要你叫startActivityForResult()实例的片段，你不需要做 - 这是造成问题。你只需要startActivityForResult()，然后在你的活动你onActivityResult()方法，你可以实例化你的片段，如果resultCode为是RESULT_OK

protected void onActivityResult(int requestCode, int resultCode, Intent data) { 
    if (requestCode == your_request_code_here) { 
     if (resultCode == Activity.RESULT_OK) { 

getSupportFragmentManager().beginTransaction().replace(R.id.content,new ServerFragment()).addToBackStack(null).commit(); 
     } 
    } 
}

查看堆栈跟踪 – Stefan

答

我认为你应该使用广播接收器注册事件蓝牙。在你的Manifest.xml，你需要添加两个声明：

<uses-permission android:name="android.permission.BLUETOOTH" /> 
<receiver android:name=".BluetoothBroadcastReceiver" 
       android:label="@string/app_name"> 
     <intent-filter> 
      <action android:name="android.bluetooth.adapter.action.STATE_CHANGED" /> 
</intent-filter> 
    </receiver>

然后，你需要实现的onReceive（）方法：

public void onReceive(Context context, Intent intent) { 

    String action = intent.getAction(); 
    Log.d("BroadcastActions", "Action "+action+"received"); 
    int state; 
    BluetoothDevice bluetoothDevice; 

    switch(action) 
    { 
     case BluetoothAdapter.ACTION_STATE_CHANGED: 
      state = intent.getIntExtra(BluetoothAdapter.EXTRA_STATE, -1); 
      if (state == BluetoothAdapter.STATE_OFF) 
      { 
       Toast.makeText(context, "Bluetooth is off", Toast.LENGTH_SHORT).show(); 
       Log.d("BroadcastActions", "Bluetooth is off"); 
      } 
      else if (state == BluetoothAdapter.STATE_TURNING_OFF) 
      { 
       Toast.makeText(context, "Bluetooth is turning off", Toast.LENGTH_SHORT).show(); 
       Log.d("BroadcastActions", "Bluetooth is turning off"); 
      } 
      else if(state == BluetoothAdapter.STATE_ON) 
      { 
getActivity().getSupportFragmentManager().beginTransaction().replace(R.id.content,new ServerFragment()).addToBackStack(null).commit(); 
       Log.d("BroadcastActions", "Bluetooth is on"); 
      } 
      break; 

.... 
}

你可以看到更多的在这个环节：Android Broadcast Receiver bluetooth events catching

如何等待onActivityResult完成？

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