从 BroadCastReceiver 更新 UI

Question

如何从 BroadCastReceiver 更新主线程。我有一个接收字符串的 BroadCastReceiver，我需要在我的 MainActivity 上设置文本视图的文本，当我在 onReceive 方法上执行 findViewById(R.id.textView); 它 returns null.

这是我的 MainActivity onCreate。

public class MainActivity extends Activity {

......

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

IntentFilter broadcastFilter = new IntentFilter(ResponseReceiver.LOCAL_ACTION); 
receiver = new ResponseReceiver();
LocalBroadcastManager localBroadcastManager =   LocalBroadcastManager.getInstance(this);
localBroadcastManager.registerReceiver(receiver, broadcastFilter);

Intent msgIntent = new Intent(MainActivity.this, IntentService.class);
msgIntent.putExtra(StockDataIntentService.PARAM_IN_MSG, getResources().getString(R.string.url));
      startService(msgIntent);

    }

public class ResponseReceiver extends BroadcastReceiver {

 public static final String LOCAL_ACTION =   "com.mypackage.ALL_DONE";
 private Handler handler;

 @Override
 public void onReceive(Context context, Intent intent) {
   String text =intent.getStringExtra(IntentService.PARAM_OUT_MSG);
   TextView txtError = (TextView) findViewById(R.id.error);
      }
  }

此 question was having exact same issue, the accepted answer explains to use a handler etc.. But reading the comments on the answer explain the BroadastReceiver runs on the main thread 的 OP，因此没有理由使用处理程序。为什么我无法在文本视图上设置文本？

Answer 1

when I do findViewById(R.id.textView); on the onReceive method it returns null.

因为目前没有调用 Activity 的 onCreate 方法中的 setContentView 方法来设置当前 Activity

的布局

因此，在 onCreate 中调用 setContentView，方法是传递布局，其中 error TextView 可用

从 BroadCastReceiver 更新 UI

update UI from BroadCastReceiver

java

android

broadcastreceiver