Question

我的应用程序发生了一些奇怪的事情。我正在尝试通过执行以下操作通过广播发送字符串：

第一步（发送）：

    Intent intent = new Intent("INFO");
    intent.putExtra("INFO_VALUE", "hello_world_2019");

第二步（接收）：

       if ("INFO".equals(intent.getAction())) {
                String abc = intent.getStringExtra("INFO_VALUE");
                Log.i(TAG, "" + abc);
        }

执行上述步骤后，我在abc字段中输入了空值。另外，如果我使用调试器并检查与第二步相关的意图，则会得到：

intent -> mExtras -> mMap -> value[0] -> name: "hello_world_2019"

我对正在发生的事情感到困惑。 abc字段不应为空，但在这种情况下为空。

如何填充上述字段，使其不为null？

Answer 1

请解释一下您到底想做什么，如果您想将数据从一项活动发送给我的朋友以外的其他人，这不是正确的方法。

如果要发送广播并在代码内的某处接收该广播，则需要执行以下步骤：

ReceiverActivity.java

@Override 
public void onCreate(Bundle savedInstanceState) {

  ... 

  // Register to receive messages. 
  // We are registering an observer (mMessageReceiver) to receive Intents 
  // with actions named "custom-event-name". 
  LocalBroadcastManager.getInstance(this).registerReceiver(mMessageReceiver,
      new IntentFilter("INFO"));
} 

// Our handler for received Intents. This will be called whenever an Intent 
// with an action named "custom-event-name" is broadcasted. 
private BroadcastReceiver mMessageReceiver = new BroadcastReceiver() {
  @Override 
  public void onReceive(Context context, Intent intent) {
    // Get extra data included in the Intent 
    String message = intent.getStringExtra("message");
    Log.d("receiver", "Got message: " + message);
  } 
}; 

@Override 
protected void onDestroy() { 
  // Unregister since the activity is about to be closed. 
  LocalBroadcastManager.getInstance(this).unregisterReceiver(mMessageReceiver);
  super.onDestroy(); 
}

SenderActivity.java

 private void sendMessage() { 
  Log.d("sender", "Broadcasting message");
  Intent intent = new Intent("INFO");
  // You can also include some extra data. 
  intent.putExtra("message", "Message goes here!");
  LocalBroadcastManager.getInstance(this).sendBroadcast(intent);
}

意向中的字符串消失

1 个答案: