从ASync任务加载片段

Question

我有一个异步任务，当数据加载时，它也设置了onClick星级评分栏。

当我用户点击星级评分栏时，我想加载一个新的片段。我想这一点：

package com.example.mike.beerportfoliomaterial; 

import android.app.Activity; 
import android.app.ProgressDialog; 
import android.content.Context; 
import android.content.SharedPreferences; 
import android.os.AsyncTask; 
import android.os.Bundle; 
import android.preference.PreferenceManager; 
import android.support.v4.app.Fragment; 
import android.support.v4.app.FragmentManager; 
import android.support.v4.app.FragmentTransaction; 
import android.util.Log; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.AdapterView; 
import android.widget.Button; 
import android.widget.ListView; 
import android.widget.RatingBar; 
import android.widget.TextView; 

import org.apache.http.HttpEntity; 
import org.apache.http.HttpResponse; 
import org.apache.http.StatusLine; 
import org.apache.http.client.HttpClient; 
import org.apache.http.client.methods.HttpGet; 
import org.apache.http.impl.client.DefaultHttpClient; 
import org.json.JSONObject; 

import java.io.BufferedReader; 
import java.io.InputStream; 
import java.io.InputStreamReader; 
import java.util.ArrayList; 
import java.util.List; 

/** 
* Created by Mike on 6/22/15. 
*/ 
public class getReviewToRateJSON extends AsyncTask<String, Void, String> { 

    Context c; 
    String noteWriter; 
    String noteID; 
    private ProgressDialog Dialog; 

    public getReviewToRateJSON(Context context) 
    { 
     c = context; 
     Dialog = new ProgressDialog(c); 
    } 

    @Override 
    protected String doInBackground(String... arg0) { 
     // TODO Auto-generated method stub 
     return readJSONFeed(arg0[0]); 
    } 

    protected void onPreExecute() { 
     Dialog.setMessage("Getting A Taste Note"); 

     Dialog.setTitle("Loading"); 
     Dialog.show(); 
    } 

    protected void onPostExecute(String result){ 
     //decode json here 
     try{ 
      JSONObject jsonObject = new JSONObject(result); 

      noteWriter = jsonObject.getString("reviewer"); 
      String beer = jsonObject.getString("beer"); 
      noteID = jsonObject.getString("noteID"); 
      String noteToRead = jsonObject.getString("note"); 

      TextView note = (TextView) ((Activity) c).findViewById(R.id.reviewToRate); 
      note.setText(noteToRead); 







     } 
     catch(Exception e){ 

     } 


     //todo: url to send rating too 

     addListenerOnRatingBar(c); 

     Dialog.dismiss(); 

    } 

    public String readJSONFeed(String URL) { 
     StringBuilder stringBuilder = new StringBuilder(); 
     HttpClient httpClient = new DefaultHttpClient(); 
     HttpGet httpGet = new HttpGet(URL); 
     try { 
      HttpResponse response = httpClient.execute(httpGet); 
      StatusLine statusLine = response.getStatusLine(); 
      int statusCode = statusLine.getStatusCode(); 
      if (statusCode == 200) { 
       HttpEntity entity = response.getEntity(); 
       InputStream inputStream = entity.getContent(); 
       BufferedReader reader = new BufferedReader(
         new InputStreamReader(inputStream)); 
       String line; 
       while ((line = reader.readLine()) != null) { 
        stringBuilder.append(line); 
       } 
       inputStream.close(); 
      } else { 
       Log.d("JSON", "Failed to download file"); 
      } 
     } catch (Exception e) { 
      Log.d("readJSONFeed", e.getLocalizedMessage()); 
     } 
     return stringBuilder.toString(); 
    } 

    private void addListenerOnRatingBar(final Context view) { 
     RatingBar ratingBar = (RatingBar) ((Activity) view).findViewById(R.id.reviewRatingBar); 

     ratingBar.setOnRatingBarChangeListener(new RatingBar.OnRatingBarChangeListener() { 
      public void onRatingChanged(RatingBar ratingBar, float rating, 
             boolean fromUser) { 

       //next async task to update online database 
       float stars = ratingBar.getRating(); 

       String s = Float.toString(stars); 
       //get user id 
       SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(c); 
       String userName = prefs.getString("userName", null); 
       final String userID = prefs.getString("userID", null); 

       String url = "myURL; 

       //async task to update rating in database 
       new AddNoteRate(c).execute(url); 



       Fragment Fragment_four; 
       FragmentManager man= ((Activity) view).getSupportFragmentManager(); 
       FragmentTransaction tran = man.beginTransaction(); 
       Fragment_four = new RateReviews(); 
       tran.replace(R.id.main, Fragment_four);//tran. 
       tran.addToBackStack(null); 
       tran.commit(); 



      } 
     }); 
    } 

} 

我最大的问题是我CA没有得到它加载在这些线路上一个新片段：

Fragment Fragment_four; 
        FragmentManager man= ((Activity) view).getSupportFragmentManager(); 
        FragmentTransaction tran = man.beginTransaction(); 
        Fragment_four = new RateReviews(); 
        tran.replace(R.id.main, Fragment_four);//tran. 
        tran.addToBackStack(null); 
        tran.commit(); 

我得到的这条线是“无法解析法”的错误：

FragmentManager man= ((Activity) view).getSupportFragmentManager(); 

我也尝试将getSupportFragmentManager更改为getFragmentManager，neith工作。

Answer 1

活动没有getSupportFragmentManager函数。 v4支持库中的FragmentActivity类可以。把它作为代替，并确保你的实际活动来自于它，而不是来自活动。

备注 - 这可能会失败。上下文不一定是一个活动。事实上，它经常会被包装在ContextWrapper或ContextThemeWrapper中。无论哪种情况，这段代码都会失败。

Answer 2

你应该做一个构造中的AsyncTask，通过活动作为参数。

AsyncTask.class

public class AsyncTaskExample extends AsyncTask<String, Integer, String> 
{ 
    Activity atv; 
    public AsyncTaskExample (Activity atv) 
    { 
      this.atv = atv; 
    } 
    @Override 
    protected void onPostExecute(String result) // contain according to regCheck.php 
    { 
      FragmentManager fragmentManager; 
      fragmentManager = atv.getFragmentManager(); 
      fragmentManager.beginTransaction() 
         .replace(R.id.main, Fragment_four) 
         .commit(); 
    } 
} 

片段传递

AsyncTaskExample task = new AsyncTaskExample(getActivity());