Android 完成服务后onReceiveResult中未更新UI组件

您好，我正在使用服务从url加载数据，如本教程所示

我有两项活动。第一个用于参加启动服务的活动，第二个用于启动服务。当我从第二个活动启动服务并在那里等待直到服务完成时，ui组件得到正确更新

但当我从第二个活动启动服务，完成服务并再次启动第二个活动时，当服务完成时，UI组件不会得到更新。但是获取的数据正确地到达onReceiveResult，只有UI视图没有得到更新

为什么会这样？我怎样才能解决这个问题

我的代码：

    @Override
    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
     /* Allow activity to show indeterminate progressbar */
    requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);
    setContentView(R.layout.activity_my);

    btnStartserv=(Button)findViewById(R.id.buttonserv);

      /* Initialize listView */
    //listView = (ListView) findViewById(R.id.listView);

    /* Starting Download Service */
    mReceiver = new DownloadResultReceiver(new Handler());
    mReceiver.setReceiver(MyActivity.this);

    btnStartserv.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            Toast.makeText(MyActivity.this,"Service Started",Toast.LENGTH_SHORT).show();
            Intent intent = new Intent(Intent.ACTION_SYNC, null, MyActivity.this, DownloadService.class);

             /* Send optional extras to Download IntentService */
            intent.putExtra("url", url);
            intent.putExtra("receiver", mReceiver);
            intent.putExtra("requestId", 101);

            startService(intent);



        }
    });
}

收到结果：

 @Override
 public void onReceiveResult(int resultCode, Bundle resultData) {
    switch (resultCode) {
        case DownloadService.STATUS_RUNNING:

            setProgressBarIndeterminateVisibility(true);
            break;
        case DownloadService.STATUS_FINISHED:

            setContentView(R.layout.activity_my);

            Toast.makeText(MyActivity.this,"Service Finished",Toast.LENGTH_SHORT).show();

            /* Hide progress & extract result from bundle */
            setProgressBarIndeterminateVisibility(false);

            String[] results = resultData.getStringArray("result");

            System.out.println("size"+results.length);

            listView = (ListView) findViewById(R.id.listView);

            if(listView == null ){
                System.out.println("listview is null");

            }else{
                System.out.println("listview is NOT NULL");

            }

            btnStartserv=(Button)findViewById(R.id.buttonserv);
            btnStartserv.setText("Service Finished!!!");

            /* Update ListView with result */
            arrayAdapter = new ArrayAdapter(MyActivity.this,       android.R.layout.simple_list_item_1, results);
            listView.setAdapter(arrayAdapter);

            break;
        case DownloadService.STATUS_ERROR:
            /* Handle the error */
            String error = resultData.getString(Intent.EXTRA_TEXT);
            Toast.makeText(this, error, Toast.LENGTH_LONG).show();
            break;
    }
} 

编辑：添加了DownloadResultReceiver类

下载ResultReceiver：

public class DownloadResultReceiver extends ResultReceiver {
private Receiver mReceiver;

public DownloadResultReceiver(Handler handler) {
    super(handler);
}

public void setReceiver(Receiver receiver) {
    mReceiver = receiver;
}

public interface Receiver {
    public void onReceiveResult(int resultCode, Bundle resultData);
}

@Override
protected void onReceiveResult(int resultCode, Bundle resultData) {
    if (mReceiver != null) {
        mReceiver.onReceiveResult(resultCode, resultData);
    }
}

---

}

什么是DownloadResultReceiver？@pskink我已经更新了这个问题。添加了DownloadResultReceiver class.inside onReceiveResult Log.d mReceiver的值，它将解释为什么在onReceiveResult中会发生这种情况。我将此日志放入了@pskink.emReceiver，mReceiver.toString；这是输出日志E/mReceiver com.example.qa_2.materialdesign.service。DownloadResultReceiver@41f66d50@请停止我的活动。公共类MyActivity扩展活动实现DownloadResultReceiver.Receiver