CustomAdapter不在列表中顯示arraylist項目

我只是擺弄並試圖解析來自示例url的JSON數據到我的app.After解析後我想顯示列表上的項目。我使用自定義adapter.List是顯示空的沒有數據inside.But調試顯示我從url成功獲取數據。問題在哪裏？（調試）：添加此代碼（然後將其刪除），以查看哈希表對象是否被正確添加到ArrayList中。將HashMap對象添加到List中沒有問題。CustomAdapter不在列表中顯示arraylist項目

for (HashMap<String, String> map : blogPosts) 
        for (Map.Entry<String, String> mapEntry : map.entrySet()) 
        { 
         String key = mapEntry.getKey(); 
         String value = mapEntry.getValue(); 
         Log.v(TAG,"Debugging2" +key); 
         Log.v(TAG,"Debugging2" +value); 
        }

這裏是main_activity：

package blogreader.com.example.android.blogreader; 


import android.app.AlertDialog; 
import android.app.ListActivity; 
import android.content.Context; 
import android.net.ConnectivityManager; 
import android.net.NetworkInfo; 
import android.os.AsyncTask; 
import android.os.Bundle; 
import android.text.Html; 
import android.util.Log; 
import android.view.Menu; 
import android.view.View; 
import android.widget.ProgressBar; 
import android.widget.SimpleAdapter; 
import android.widget.TextView; 
import android.widget.Toast; 

import org.json.JSONArray; 
import org.json.JSONException; 
import org.json.JSONObject; 

import java.io.IOException; 
import java.io.InputStream; 
import java.io.InputStreamReader; 
import java.io.Reader; 
import java.net.HttpURLConnection; 
import java.net.MalformedURLException; 
import java.net.URL; 
import java.util.ArrayList; 
import java.util.HashMap; 

public class MainListActivity extends ListActivity { 


    public static final int NUMBER_OF_POSTS = 20; 
    public static final String TAG = MainListActivity.class.getSimpleName(); 
    protected JSONObject mBlogData; 
    protected ProgressBar mProgressBar; 
    private final String KEY_TITLE="title"; 
    private final String KEY_AUTHOR="author"; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main_list); 
     mProgressBar = (ProgressBar) findViewById(R.id.progressBar1); 

     if(isNetworkAvaliable()){ 
      mProgressBar.setVisibility(View.VISIBLE); 
      GetBlogPostsTask getBlogPostsTask = new GetBlogPostsTask(); 
      getBlogPostsTask.execute();//calls Asynchronus class's doInbackGround 
     }else{ 
      Toast.makeText(this, "Network Unavailable!", Toast.LENGTH_LONG).show(); 
     } 

     //Toast.makeText(this, getString(R.string.no_items), Toast.LENGTH_LONG).show(); 
    } 


    private boolean isNetworkAvaliable() { 
     ConnectivityManager manager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE); 
     NetworkInfo networkInfo= manager.getActiveNetworkInfo(); 

     boolean isAvailable = false; 
     if(networkInfo != null && networkInfo.isConnected()){ 
      isAvailable = true; 
     } 

     return isAvailable; 

    } 


    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     // Inflate the menu; this adds items to the action bar if it is present. 
     getMenuInflater().inflate(R.menu.menu_main_list, menu); 
     return true; 
    } 

    private void handleBlogResponse() 
    { 

     mProgressBar.setVisibility(View.INVISIBLE); 
     if (mBlogData == null) 
     { 
      // TODO: handle errors 
      updateDisplayForError(); 

     } 
     else 
     { 
      try { 
      JSONArray jsonPosts = mBlogData.getJSONArray("posts"); 
       ArrayList<HashMap<String, String>> blogPosts = 
         new ArrayList<HashMap<String, String>>(); 

      for (int i = 0; i < jsonPosts.length(); i++) { 
       JSONObject post = jsonPosts.getJSONObject(i); 
       String title = post.getString(KEY_TITLE); 
       title= Html.fromHtml(title).toString();//check escape characters 
       String author = post.getString(KEY_AUTHOR); 
       author = Html.fromHtml(author).toString(); 

       HashMap<String,String> blogPost=new HashMap<String,String>(); 
       blogPost.put(KEY_TITLE,title); 
       blogPost.put(KEY_AUTHOR,author); 
       blogPosts.add(blogPost);//addding hashmap object to arraylist 

      } 
       String[] keys={"KEY_TITLE","KEY_AUTHOR"}; 
       int [] ids={android.R.id.text1,android.R.id.text2}; 
       SimpleAdapter adapter =new SimpleAdapter(this,blogPosts,android.R.layout.simple_list_item_2,keys,ids); 
       setListAdapter(adapter); 

     } catch (JSONException e) { 
      Log.e(TAG, "Exception Caught", e); 

     } 
    } 
    } 

    private void updateDisplayForError() { 
     AlertDialog.Builder builder=new AlertDialog.Builder(this); 
     builder.setTitle(getString(R.string.error_title)); 
     builder.setMessage(getString(R.string.error_message)); 
     builder.setPositiveButton(android.R.string.ok, null); 
     AlertDialog dialogue=builder.create(); 
     dialogue.show(); 
     TextView emptyTextView= (TextView) getListView().getEmptyView(); 
     emptyTextView.setText(getString(R.string.no_items)); 
    } 

    private class GetBlogPostsTask extends AsyncTask<Object, Void,JSONObject> { 

     @Override 
     protected JSONObject doInBackground(Object... arg0) { 
      int responseCode = -1; 
      JSONObject jsonResponse=null; 
      try { 
       URL blogFeedUrl = new URL("http://blog.teamtreehouse.com/api/get_recent_summary/?count=" + NUMBER_OF_POSTS); 
       HttpURLConnection connection = (HttpURLConnection) blogFeedUrl.openConnection(); 
       connection.connect(); 

       responseCode = connection.getResponseCode(); 
       if (responseCode == HttpURLConnection.HTTP_OK) { 
        InputStream inputStream = connection.getInputStream(); 
        Reader reader = new InputStreamReader(inputStream); 
        int nextCharacter; // read() returns an int, we cast it to char later 
        String responseData = ""; 
        while(true){ // Infinite loop, can only be stopped by a "break" statement 
         nextCharacter = reader.read(); // read() without parameters returns one character 
         if(nextCharacter == -1) // A return value of -1 means that we reached the end 
          break; 
         responseData += (char) nextCharacter; // The += operator appends the character to the end of the string 
        } 

        jsonResponse = new JSONObject(responseData); 
        String status = jsonResponse.getString("status"); 
        Log.v(TAG, status); 

        JSONArray jsonPosts = jsonResponse.getJSONArray("posts"); 
        for (int i = 0; i < jsonPosts.length(); i++) 
        {//just for debugging 
         JSONObject jsonPost = jsonPosts.getJSONObject(i); 
         String title = jsonPost.getString("title"); 
         Log.v(TAG, "Post " + i + ": " + title); 
        } 
       } 
       else { 
        Log.i(TAG, "Unsuccessful HTTP Response Code: " + responseCode); 
       } 


      } 
      catch (MalformedURLException e) { 
       Log.e(TAG, "URLException caught: "+e, e); 
      } 
      catch (IOException e) { 
       Log.e(TAG, "IOException caught: "+e, e); 
      } 
      catch (Exception e) { 
       Log.e(TAG, "Exception caught: "+e, e); 
      } 

      return jsonResponse; 
     } 
     @Override 
     protected void onPostExecute(JSONObject result){ 
      mBlogData=result;//This class is a bridge between AsyncTask class and Main 
      handleBlogResponse(); 

     } 
    } 



}

這裏是logcat的：

09-22 21:09:09.910 11081-11081/blogreader.com.example.android.blogreader I/art﹕ Late-enabling -Xcheck:jni 
09-22 21:09:09.954 11081-11091/blogreader.com.example.android.blogreader E/art﹕ Failed sending reply to debugger: Broken pipe 
09-22 21:09:09.955 11081-11091/blogreader.com.example.android.blogreader I/art﹕ Debugger is no longer active 
09-22 21:09:10.067 11081-11110/blogreader.com.example.android.blogreader D/OpenGLRenderer﹕ Use EGL_SWAP_BEHAVIOR_PRESERVED: true 
09-22 21:09:10.106 11081-11081/blogreader.com.example.android.blogreader D/Atlas﹕ Validating map... 
09-22 21:09:10.209 11081-11110/blogreader.com.example.android.blogreader I/Adreno-EGL﹕ <qeglDrvAPI_eglInitialize:410>: EGL 1.4 QUALCOMM build: AU_LINUX_ANDROID_LA.BF.1.1.1_RB1.05.00.02.042.016_msm8226_LA.BF.1.1.1_RB1__release_AU() 
    OpenGL ES Shader Compiler Version: E031.25.03.00 
    Build Date: 02/11/15 Wed 
    Local Branch: 
    Remote Branch: quic/LA.BF.1.1.1_rb1.10 
    Local Patches: NONE 
    Reconstruct Branch: AU_LINUX_ANDROID_LA.BF.1.1.1_RB1.05.00.02.042.016 + 62ca4eb + acd831d + 9f8b442 + e027a02 + cba30ba + 53c303a + a649d79 + 23e16f8 + 5e97da7 + cbd2a44 + 33d072a + 7aacf06 + 72b33e7 + 28f6f60 + b4c13d8 + NOTHING 
09-22 21:09:10.216 11081-11110/blogreader.com.example.android.blogreader I/OpenGLRenderer﹕ Initialized EGL, version 1.4 
09-22 21:09:10.302 11081-11110/blogreader.com.example.android.blogreader D/OpenGLRenderer﹕ Enabling debug mode 0 
09-22 21:09:15.607 11081-11096/blogreader.com.example.android.blogreader W/art﹕ Suspending all threads took: 5.419ms 
09-22 21:09:16.618 11081-11108/blogreader.com.example.android.blogreader V/MainListActivity﹕ ok 
09-22 21:09:16.618 11081-11108/blogreader.com.example.android.blogreader V/MainListActivity﹕ Post 0: Asset Workflow for Game Art: 3D Modeling 
09-22 21:09:16.619 11081-11108/blogreader.com.example.android.blogreader V/MainListActivity﹕ Post 1: New Course Roundup: JavaFX, WooCommerce, Java Loops and The CSS calc() Function 
09-22 21:09:16.619 11081-11108/blogreader.com.example.android.blogreader V/MainListActivity﹕ Post 2: Mastering Meetups for Maximum Merriment 
09-22 21:09:16.619 11081-11108/blogreader.com.example.android.blogreader V/MainListActivity﹕ Post 3: The 10 Most Influential Figures in Web Design 
09-22 21:09:16.619 11081-11108/blogreader.com.example.android.blogreader V/MainListActivity﹕ Post 4: Jeanne Learned Swift and Used Her Free Time to Create and Launch a Unique iPhone App 
09-22 21:09:16.619 11081-11108/blogreader.com.example.android.blogreader V/MainListActivity﹕ Post 5: New Course Roundup: Foundations for Apps, Drupal, 3D Art with Maya LT, Future Insights Live and More 
09-22 21:09:16.619 11081-11108/blogreader.com.example.android.blogreader V/MainListActivity﹕ Post 6: Keeping Up With Java 
09-22 21:09:16.619 11081-11108/blogreader.com.example.android.blogreader V/MainListActivity﹕ Post 7: Ricky is a High School Senior With a Successful Freelance Web Design and Development Business 
09-22 21:09:16.619 11081-11108/blogreader.com.example.android.blogreader V/MainListActivity﹕ Post 8: Your First Job May Not Be Your Dream Job 
09-22 21:09:16.619 11081-11108/blogreader.com.example.android.blogreader V/MainListActivity﹕ Post 9: Ultimate Guide to User Feedback Part 2: 10 Ways to Get User Feedback 
09-22 21:09:16.619 11081-11108/blogreader.com.example.android.blogreader V/MainListActivity﹕ Post 10: Creating Customized Shelf Buttons and Hotkeys in Maya LT 
09-22 21:09:16.619 11081-11108/blogreader.com.example.android.blogreader V/MainListActivity﹕ Post 11: The Scrum Sniff Test 
09-22 21:09:16.619 11081-11108/blogreader.com.example.android.blogreader V/MainListActivity﹕ Post 12: 15-Year-Old Harry Learned to Code, Gained Industry Experience and is Well on His Way to a Future in Tech 
09-22 21:09:16.619 11081-11108/blogreader.com.example.android.blogreader V/MainListActivity﹕ Post 13: How to Use Image Effects in Unity 
09-22 21:09:16.619 11081-11108/blogreader.com.example.android.blogreader V/MainListActivity﹕ Post 14: New Course Roundup: Functional Python, Tkinter, Ruby, WordPress and More 
09-22 21:09:16.619 11081-11108/blogreader.com.example.android.blogreader V/MainListActivity﹕ Post 15: What Every Junior iOS Developer Needs to Know 
09-22 21:09:16.619 11081-11108/blogreader.com.example.android.blogreader V/MainListActivity﹕ Post 16: Go Back to School With Treehouse 
09-22 21:09:16.619 11081-11108/blogreader.com.example.android.blogreader V/MainListActivity﹕ Post 17: How to be a Resourceful Indie Game Developer 
09-22 21:09:16.619 11081-11108/blogreader.com.example.android.blogreader V/MainListActivity﹕ Post 18: New Course Roundup: How to Make a Video Game and Express Basics 
09-22 21:09:16.619 11081-11108/blogreader.com.example.android.blogreader V/MainListActivity﹕ Post 19: Learn Game Development at Treehouse!

來源

2015-09-22 user3847870

你在使用模擬器嗎？ – Aakash

您的SimpleAdapter類在哪裏 –

@Aakash我正在使用我的物理設備。模擬器太慢了。我嘗試使用GenyMotion，但我更喜歡我的設備。 – user3847870

嘗試添加此行

onContentChanged();

後

setListAdapter(adapter);

這將強制您的活動更新列表，因爲它的內容已更改。

來源

2015-09-22 16:00:17

對不起，我仍然得到一個空的列表。 – user3847870

終於解決了它，它一直在我的鼻子下!!!這麼愚蠢的錯誤。我在已經是字符串類型KEY_AUTHOR和KEY_VALUE上增加了額外的「」。作爲結果傳遞給SimpleAdapter的鍵和值參數因此而混亂作爲適配器顯示空列表無法理解的關鍵，價值pair.Thank你的人爲您的時間!!!。 – user3847870

@ user3847870太好了 –

CustomAdapter不在列表中顯示arraylist項目

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