Question

我在AysncTask中的应用程序的本地数据库中插入了一些数据，但是当执行该类时，屏幕上没有显示进度对话框，而我可以看到正在运行的日志。我看到很多相关的答案，但问题没有解决。我读了.get（）方法阻止了ui，但我已经没有使用这个方法了。我不知道为什么它没有在屏幕上显示

从主Activity调用异步类

 AsyncGetDataFromServer task = new AsyncGetDataFromServer(this);
 task.execute();

AsyncTask类的代码

public class AsyncGetDataFromServer extends AsyncTask<Void, Void, Boolean> {

ProgressDialog pd;
Context cxt;
DatabaseHandler dbHelper;
private static ArrayList<DataModel> categoryArrayList;

public AsyncGetDataFromServer(Context context) {
    // TODO Auto-generated constructor stub
    cxt= context;
    pd = new ProgressDialog(cxt);
    pd.setTitle("Please wait");
    pd.setMessage("Loading...");
    pd.setCancelable(false);
    dbHelper = new DatabaseHandler(cxt);
}

@Override
protected Boolean doInBackground(Void... params)
{
    try {
        Log.d("do in background","true");

                for (int i = 0; i < response.body().getVideoEntity().size(); i++) {
                    //inserting in categories
                    VideoEntity videoEntity;
                    videoEntity = response.body().getVideoEntity().get(i);
                    dbHelper.insertChannels(videoEntity);
                }        
            }

    } catch (Exception e) {
        // TODO Auto-generated catch block
        Log.e("exception error", e.getMessage());
    }

    return true;
}

@Override
protected void onPreExecute() {
    super.onPreExecute();
    Log.d("on pre execute","true");
    pd.show();
}

@Override
protected void onPostExecute(Boolean result) {
    super.onPostExecute(result);
    Log.d("on post execute","true");
    pd.dismiss();
}

}

Answer 1

将Activity而不是上下文传递给构造函数。例如 -

    AsyncGetDataFromServer task = new AsyncGetDataFromServer(MyActivity.this);
 task.execute();

Answer 2

您应该实施方法onProgressUpdate并使用方法publishProgress：

请参阅https://developer.android.com/reference/android/os/AsyncTask.html

Answer 3

在onPreExecute（）方法中显示对话框＆amp;在onPostExecute（）方法中解雇：

private class AsyncGetDataFromServer extends AsyncTask<Void, Void, Boolean> {
  private final ProgressDialog dialog = new ProgressDialog(YourClass.this);

  protected void onPreExecute() {
     this.dialog.setMessage("Loading...");
     this.dialog.show();
  }

  protected void doInBackground(final Void unused) {
     //don't interact with the ui!
  }

  protected void onPostExecute(final Boolean result) {
     if (this.dialog.isShowing()) {
        this.dialog.dismiss();
     }
  }
}

进度对话框未出现在AsynTask内的数据库操作中

3 个答案: