Asynctask : doInBackground에서 onPostExecute로 값을 전달하십시오.

Question

Java 프로그래밍에 새로운 것이므로 질문이 있습니다. this 게시물을 발견하고이 메소드를 사용하여 doInBackground 메소드의 값을 onPostExecute 메소드에 전달하려고했습니다. 그러나 Android Studio 2.3에서는 허용하지 않습니다.

안드로이드 스튜디오 onPostExecute에서 내 @Override을 강조 :

@Override 
    protected void onPostExecute(String s){ 
     //super.onPreExecute(); 

     // Create adapter for ListView (Universal Image Loader) 
     AngeboteListAdapter adapter = new AngeboteListAdapter(this, R.layout.angebote_list_view_adapter, dataList); 
     mListView.setAdapter(adapter); 

     Toast.makeText(AngeboteActivity.this,"onPostExecute",Toast.LENGTH_LONG).show(); 
    } 

및 doInBackground 내 QueryResult을 :

public class MultiplyTask extends AsyncTask<String,Void,ArrayList<Artikel>>{ 

    private class QueryResult { 
     ArrayList<Artikel> dataList; 

     public QueryResult(ArrayList<Artikel> dataList) { 
      this.dataList = dataList ; 
     } 
    } 

    @Override 
    protected void onPreExecute(){ 
     super.onPreExecute(); 
    } 
    @Override 
    protected void onPostExecute(String s){ 
     //super.onPreExecute(); 

     // Create Adapter for ListView (UniversalImageLoader) 
     AngeboteListAdapter adapter = new AngeboteListAdapter(this, R.layout.angebote_list_view_adapter, dataList); 
     mListView.setAdapter(adapter); 

     Toast.makeText(AngeboteActivity.this,"onPostExecute",Toast.LENGTH_LONG).show(); 
    } 


    String data =""; 

    @Override 
    protected QueryResult doInBackground(String... params){ 
     try 
     { 
     URL url = new URL("https://myjson.com"); 
     HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection(); 
     InputStream inputStream = httpURLConnection.getInputStream(); 
     BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream)); 
     String line = ""; 
     while(line != null){ 
       line = bufferedReader.readLine(); 
       data = data + line; 
     } 
     ArrayList<String> listdata = new ArrayList<>(); 
     JSONArray jArray = new JSONArray(data); 
     for(int i =0 ;i <jArray.length(); i++){ 
      listdata.add(jArray.getString(i)); 
     } 

      JSONArray json = new JSONArray(data); 
      String[][] matrix = new String[json.length()][5]; 


     //Fill Array with response 
     for (int i=0; i < json.length(); i++) { 
      JSONObject obj = json.getJSONObject(i); 
      matrix[i][0] = String.valueOf(obj.getInt("Artikelnummer")); 
      matrix[i][1] = String.valueOf(obj.getDouble("Preis")); 
      matrix[i][2] = obj.getString("Von"); 
      matrix[i][3] = obj.getString("Bis"); 
      matrix[i][4] = obj.getString("art_link"); 
     } 



      //new Arrays 
      String[] all_art_nr = new String[matrix.length]; 
      String[] all_preis = new String[matrix.length]; 
      String[] all_von = new String[matrix.length]; 
      String[] all_bis = new String[matrix.length]; 
      String[] all_link = new String[matrix.length]; 


      //Array sort 
      for (int i = 0; i < matrix.length; i++) { 
       all_art_nr[i] = matrix[i][0]; 
       all_preis[i] = matrix[i][1]; 
       all_von[i] = matrix[i][2]; 
       all_bis[i] = matrix[i][3]; 
       all_link[i] = matrix[i][4]; 
      } 



      //Fill Arraylist 
      ArrayList<Artikel> dataList = new ArrayList<>(); 
      for (int i = 0; i < matrix.length; i++) { 
       Artikel angebote = new Artikel(all_art_nr[i], all_preis[i], all_von[i], all_bis[i], all_link[i]); 
       dataList.add(angebote); 
      } 


      return new QueryResult(dataList); 


    } catch (IOException e) { 
      e.printStackTrace(); 
     } catch (JSONException e) { 
      e.printStackTrace(); 
     } 

    return null; 
    } 

} 

안드로이드 스튜디오가 원하는 :

여기

@Override 
    protected QueryResult doInBackground(String... params){ 
     try 
     { 

모든 코드 QueryResult를 Arraylist로 바꾸고 @Override가 supercla의 메소드를 오버라이드하지 않습니다. ss, doINBackground에서 QueryResult를 꺼내면 수퍼 클래스 메서드를 재정의 할 수 있습니다. 미리 감사드립니다.

Answer 1

당신 은 AsyncTask를 검사에게 매개 변수 확장 할 때 : 그래서 당신은 당신의 onPostExecute에 QueryResult을 반환하는 당신의 doInBackround에 문자열를 전달하려면 extends Asynctask<Params, Progress, Result>

을 다음과 같이 확장해야합니다. extends Asynctask<String, Void, QueryResult>

Answer 2

왜 작동하지 않습니까?

private class QueryResult { 
    ArrayList<Artikel> dataList; 

    public QueryResult(ArrayList<Artikel> dataList) { 
     this.dataList = dataList ; 
    } 
} 



public class loadAngebote extends AsyncTask<String, Void, ArrayList<Artikel>>{ 

    String data =""; 

    @Override 
    protected ArrayList<Artikel> doInBackground(String... params){ 

     try 
     { 
      URL url = new URL("https://api.myjson.com/bins/1dnrmf"); 
      HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection(); 
      InputStream inputStream = httpURLConnection.getInputStream(); 
      BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream)); 
      String line = ""; 
      while(line != null){ 
       line = bufferedReader.readLine(); 
       data = data + line; 
      } 
      ArrayList<String> listdata = new ArrayList<>(); 
      JSONArray jArray = new JSONArray(data); 
      for(int i =0 ;i <jArray.length(); i++){ 
       listdata.add(jArray.getString(i)); 
      } 

      JSONArray json = new JSONArray(data); 
      String[][] matrix = new String[json.length()][5]; 

      //Array mit Response füllen 
      for (int i=0; i < json.length(); i++) { 
       JSONObject obj = json.getJSONObject(i); 
       matrix[i][0] = String.valueOf(obj.getInt("Artikelnummer")); 
       matrix[i][1] = String.valueOf(obj.getDouble("Preis")); 
       matrix[i][2] = obj.getString("Von"); 
       matrix[i][3] = obj.getString("Bis"); 
       matrix[i][4] = obj.getString("art_link"); 
      } 

      //Neue Arrays inizializieren 
      String[] all_art_nr = new String[matrix.length]; 
      String[] all_preis = new String[matrix.length]; 
      String[] all_von = new String[matrix.length]; 
      String[] all_bis = new String[matrix.length]; 
      String[] all_link = new String[matrix.length]; 


      //Array umsotieren und befüllen 
      for (int i = 0; i < matrix.length; i++) { 
       all_art_nr[i] = matrix[i][0]; 
       all_preis[i] = matrix[i][1]; 
       all_von[i] = matrix[i][2]; 
       all_bis[i] = matrix[i][3]; 
       all_link[i] = matrix[i][4]; 
      } 

      //String in Arraylist vom Typ Artikel einfügen 
      ArrayList<Artikel> dataList = new ArrayList<>(); 
      //ArrayList<Artikel> passed = passing[0]; //get passed arraylist 
      for (int i = 0; i < matrix.length; i++) { 
       Artikel angebote = new Artikel(all_art_nr[i], all_preis[i], all_von[i], all_bis[i], all_link[i]); 
       dataList.add(angebote); 
      } 

      return new QueryResult(dataList); 




     } catch (IOException e) { 
      e.printStackTrace(); 
     } catch (JSONException e) { 
      e.printStackTrace(); 
     } 



     return null; 
    } 

    @Override 
    protected void onPostExecute(ArrayList<Artikel> QueryResult){ 
     //super.onPreExecute(); 

     TextView txt = (TextView) findViewById(R.id.data); 
     txt.setText("Executed"); // txt.setText(result); 
     // Adapter erstellen und dem ListView übergeben 
     AngeboteListAdapter adapter = new AngeboteListAdapter(this, R.layout.angebote_list_view_adapter, dataList); 
     mListView.setAdapter(adapter); 
     Toast.makeText(AngeboteActivity.this,"onPostExecute Methode ausgeführt",Toast.LENGTH_LONG).show(); 


    } 

}