AsyncTask 的进度对话框 - Android

Progress Dialog for AsyncTask - Android

提问by user3156801

I'm trying to show a progress dialog while the twitter feed is loading up...However the progress dialog remains on screen when the twitter feed appears. Any help is much appreciated.

我正在尝试在 twitter 提要加载时显示进度对话框……但是，当 twitter 提要出现时，进度对话框仍保留在屏幕上。任何帮助深表感谢。

public class MainActivity extends ListActivity {

    final static String twitterScreenName = "CFABUK";
    final static String TAG = "MainActivity";
    private AsyncTask<Object, Void, ArrayList<TwitterTweet>> tat;
    boolean done;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        done=false;
        AndroidNetworkUtility androidNetworkUtility = new AndroidNetworkUtility();
        if (androidNetworkUtility.isConnected(this)) {
            TwitterAsyncTask syn=new TwitterAsyncTask();
            syn.execute(twitterScreenName,this);


            ProgressDialog pd = new ProgressDialog(MainActivity.this);
            pd.setMessage("loading");
            pd.show();

            do {
                if(!(syn.getStatus()==AsyncTask.Status.RUNNING)) {
                pd.dismiss();
                pd.cancel();
                done=true;
                }
            } while(done=false);


        } else {
            Log.v(TAG, "Network not Available!");
        }
    }
}

回答by Slampy

You must call ProgressDialog show() method on AsyncTasks onPreExecute(). For example:

您必须在 AsyncTasks onPreExecute() 上调用 ProgressDialog show() 方法。例如：

class MyTask extends AsyncTask<Void, Void, Void> {
 ProgressDialog pd;
    @Override
    protected void onPreExecute() {
      super.onPreExecute();
       pd = new ProgressDialog(MainActivity.this);
       pd.setMessage("loading");
       pd.show();
    }

    @Override
    protected Void doInBackground(Void... params) {
      // Do your request
    }

    @Override
    protected void onPostExecute(Void result) {
      super.onPostExecute(result);
      if (pd != null)
      {
         pd.dismiss();
      }
    }
  }

回答by Yeray

You must use a onPreExecute and onPostExecute of AsyncTask class. For example:

您必须使用 AsyncTask 类的 onPreExecute 和 onPostExecute。例如：

class AsyncData extends AsyncTask<Void, Void, Void>{

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        // init progressdialog
    }


    @Override
    protected Void doInBackground(Void... arg0) {
        // get data
        return null;
    }


    @Override
    protected void onPostExecute(Void result) {
        super.onPostExecute(result);
        // dismiss dialog
    }
}

回答by My God

The methods onPreExecute(), doInBackground()and onPostExecute()of AsyncTask are used for purpose that you mentioned -

的方法onPreExecute()，doInBackground()和onPostExecute()的AsyncTask的用于目的你提到的-

public class MainActivity extends ListActivity {

    final static String twitterScreenName = "CFABUK";
    final static String TAG = "MainActivity";
    private AsyncTask<Object, Void, ArrayList<TwitterTweet>> tat;
    boolean done;
    Context context;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        done=false;
        context = this;
        new NetworkTask().execute();
    }
}


class NetworkTask extends AsyncTask<String, String, String> 
{

  Context ctx = context ;

  @Override
  protected void onPreExecute() 
  {
    super.onPreExecute();
    pDialog = new ProgressDialog(getActivity());
    pDialog.setMessage("Working ...");
    pDialog.setIndeterminate(false);
    pDialog.setCancelable(false);
    pDialog.show();
}

@Override
protected String doInBackground(String... args) 
{

    //Do your background work here and pass the value to onPostExecute

    AndroidNetworkUtility androidNetworkUtility = new AndroidNetworkUtility();

    if (androidNetworkUtility.isConnected(ctx)) {
            TwitterAsyncTask syn=new TwitterAsyncTask();
            syn.execute(twitterScreenName,this);

             while(done)
             {
                if(!(syn.getStatus()==AsyncTask.Status.RUNNING)) 
                {
                   done=true;
                }
                else 
                {
                   Log.v(TAG, "Network not Available!");
                } 
             }

    return done + "";

}

protected void onPostExecute(String result) 
{

   //Do something with result and close the progress dialog

   pDialog.dismiss();

}

回答by Junaid Ali

ProgressBar is best alternative for ProgressDialog. A user interface element that indicates the progress of an operation. ProgressDialog is deprecated in latest versions.

ProgressBar 是 ProgressDialog 的最佳选择。指示操作进度的用户界面元素。ProgressDialog 在最新版本中已弃用。

For more info see android developer official site: https://developer.android.com/reference/android/widget/ProgressBar.html

有关更多信息，请参阅 android 开发者官方网站：https: //developer.android.com/reference/android/widget/ProgressBar.html