Question

我正在使用异步任务在我的列表视图中重新加载数据，并在我的活动中设置进度条以显示它正在加载。但问题是，如果我开始一个新活动并返回并且没有完成加载，则不会显示进度条。如何设置进度条以继续加载？我忘了提及，在我返回活动后，异步任务也没有刷新我的列表视图。这是我正在使用的代码：

    public class MyCollectionsTask extends AsyncTask <Context, Integer, Void> {
    @Override
    protected Void doInBackground(Context... arrContext) {
        JsonCollection jsonColl = new JsonCollection();
        Log.e("","DO IN BACKGROUND");
        for(int i=0; i<arrContext.length; i++) {
                jsonColl.executeInsert(arrContext[i]);
        }
        return null;
    }
    @Override
    protected void onProgressUpdate(Integer... progress) {
        Log.e("","ON PROGRESS UPDATE");
        for (int i=0; i<progress.length; i++){
            progressBar.setProgress(i);
        }   
    }
    @Override
    protected void onCancelled() {
        Log.e("","ON CANCELLED");
         progressBar.setVisibility(View.GONE);
         sync.setImageResource(R.drawable.sync_icon2);
    } 
    @Override
    protected void onPreExecute() 
    {
        Log.e("","ON PRE EXECUTE");
    }
    @Override
    protected void onPostExecute(Void v) {
        Log.e("","ON POST EXECUTE");
        SystemDatabaseHelper newdbHelper = new SystemDatabaseHelper(MyCollectionList.this, null, 1);
        newdbHelper.initialize(MyCollectionList.this);

        String genresSQLforID = "SELECT DISTINCT g.genre_id AS genreID, gl.title AS Title " +
               "FROM genres AS g, genre_lang AS gl " +
               "WHERE gl.genre_id = g.genre_id AND gl.lang_code ='" + langCode + "'"+" ORDER BY gl.title";
        Cursor genresCursor = newdbHelper.executeSQLQuery(genresSQLforID);
        if (genresCursor.getCount() == 0) {
           genresCursor.close();        
        } else {
           genresCursor.moveToFirst();
           GenID = Integer.parseInt(genresCursor.getString(genresCursor.getColumnIndex("genreID")));
        }
            getCollectionsForGenre(GenID);
        final SharedPreferences isLogged = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
        SharedPreferences.Editor editor = isLogged.edit();
        editor.putBoolean("getProgBarCollection", false);
        editor.commit();
        progressBar.setVisibility(View.GONE);
        sync.setImageResource(R.drawable.sync_icon2);
    }
  }

Answer 1

当你从另一个活动返回时，它只是恢复活动，它不会进入onCreate方法（）。您需要做的是使用 startActivityForResult（）从asyntask活动中启动另一个活动，并覆盖asyntask活动中的onActivityResult方法。并在 onActivityResult（）中再次执行asyntask。你做得更好，而不是在Onresume中调用asyntask，因为在其他情况下它也会像Onresume一样进入Onresume，就像按下home键再去一次

返回活动后未加载Android异步任务进度条

1 个答案: