hashmap在simpleadapter中工作，但在自定义数组适配器中不工作

Question

以下代码的Hashmap适用于simpleadapter数组，但不适用于自定义数组适配器。为什么？我该如何解决它？请帮助。无法解决。请尽一切努力。

我正在使用lazyLoading类来加载图像。

public void onItemClick(AdapterView<?> parent, View view, 
        int position, long id) { 


       HashMap<String, String> o = (HashMap<String, String>) list.getItemAtPosition(position); 
       Toast.makeText(CustomizedListView.this, "ID '" + o.get("KEY_TITLE") + "' was clicked.", Toast.LENGTH_SHORT).show(); 

      }   

，其在上述的onclick所示崩溃整个代码：

public class CustomizedListView extends Activity { 
    // All static variables 
    static final String URL = "https://itunes.apple.com/us/rss/topalbums/limit=20/json"; 
    // XML node keys 
    static final String KEY_SONG = "song"; // parent node 
    static final String KEY_ID = "id"; 
    static final String KEY_TITLE = "title"; 
    static final String KEY_ARTIST = "artist"; 
    static final String KEY_DURATION = "duration"; 
    static final String KEY_THUMB_URL = "thumb_url"; 

    ListView list; 
    LazyAdapter adapter; 

    HashMap<String, String> map; 


    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main); 


     ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>(); 

     JSONObject json = JSONfunctions.getJSONfromURL(URL); 


     try { 
      JSONObject arr2 = json.getJSONObject("feed"); 
      JSONArray arr = arr2.getJSONArray("entry"); 

      for (int i = 0; i < arr.length(); i++) { 
       JSONObject e1 = arr.getJSONObject(i); 

       JSONArray arr3 = e1.getJSONArray("im:image"); 

       JSONObject arr8 = e1.getJSONObject("im:name"); 

       JSONObject arr10 = e1.getJSONObject("im:artist"); 

        JSONObject e12 = arr3.getJSONObject(0); 

      // creating new HashMap 
      map = new HashMap<String, String>(); 

      map.put(KEY_THUMB_URL, e12.getString("label")); 

      map.put(KEY_ARTIST, arr8.getString("label")); 
      map.put(KEY_TITLE, arr10.getString("label")); 
      // adding HashList to ArrayList 
      songsList.add(map); 
      } 

     } catch (JSONException e) { 
      // Log.e("log_tag", "Error parsing data "+e.toString()); 
      Toast.makeText(getBaseContext(), 
        "Network communication error!", 5).show(); 
     } 


     list=(ListView)findViewById(R.id.list); 

     // Getting adapter by passing xml data ArrayList 
     adapter=new LazyAdapter(this, songsList);   
     list.setAdapter(adapter); 

     // Click event for single list row 
     list.setOnItemClickListener(new OnItemClickListener() { 

      @Override 
      public void onItemClick(AdapterView<?> parent, View view, 
        int position, long id) { 

           HashMap<String, String> o= (HashMap<String, String>) list.getItemAtPosition(position);     

           Toast.makeText(CustomizedListView.this, "ID '" + o.get("title") + "' was clicked.", Toast.LENGTH_SHORT).show(); 



      } 
     });  
    } 
} 

下面这段代码完美地工作：

public class Main extends ListActivity { 
    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.listplaceholder); 

     ArrayList<HashMap<String, String>> mylist = new ArrayList<HashMap<String, String>>(); 


     JSONObject json = JSONfunctions.getJSONfromURL("http://api.geonames.org/earthquakesJSON?north=44.1&south=-9.9&east=-22.4&west=55.2&username=demo"); 

     try{ 

      JSONArray earthquakes = json.getJSONArray("earthquakes"); 

      for(int i=0;i<earthquakes.length();i++){       
       HashMap<String, String> map = new HashMap<String, String>();  
       JSONObject e = earthquakes.getJSONObject(i); 

       map.put("id", String.valueOf(i)); 
       map.put("name", "Earthquake name:" + e.getString("eqid")); 
       map.put("magnitude", "Magnitude: " + e.getString("magnitude")); 
       mylist.add(map);    
      }  
     }catch(JSONException e)  { 
      Log.e("log_tag", "Error parsing data "+e.toString()); 
     } 

     ListAdapter adapter = new SimpleAdapter(this, mylist , R.layout.main, 
         new String[] { "name", "magnitude" }, 
         new int[] { R.id.item_title, R.id.item_subtitle }); 

     setListAdapter(adapter); 

     final ListView lv = getListView(); 
     lv.setTextFilterEnabled(true); 
     lv.setOnItemClickListener(new OnItemClickListener() { 
      public void onItemClick(AdapterView<?> parent, View view, int position, long id) {    
       @SuppressWarnings("unchecked") 
       HashMap<String, String> o = (HashMap<String, String>) lv.getItemAtPosition(position);     
       Toast.makeText(Main.this, "ID '" + o.get("id") + "' was clicked.", Toast.LENGTH_SHORT).show(); 

      } 
     }); 
    } 
} 

logcat的：

threadid=1: thread exiting with uncaught exception (group=0x40ab0228) 
FATAL EXCEPTION: main 
java.lang.ClassCastException: java.lang.Integer cannot be cast to java.util.HashMap 
    at com.example.androidhive.CustomizedListView$1.onItemClick(CustomizedListView.java:94) 
    at android.widget.AdapterView.performItemClick(AdapterView.java:292) 
    at android.widget.AbsListView.performItemClick(AbsListView.java:1077) 
    at android.widget.AbsListView$PerformClick.run(AbsListView.java:2533) 
    at android.widget.AbsListView$1.run(AbsListView.java:3198) 
    at android.os.Handler.handleCallback(Handler.java:605) 
    at android.os.Handler.dispatchMessage(Handler.java:92) 
    at android.os.Looper.loop(Looper.java:154) 
    at android.app.ActivityThread.main(ActivityThread.java:4945) 
    at java.lang.reflect.Method.invokeNative(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:511) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 
    at dalvik.system.NativeStart.main(Native Method) 

LazyAdapter.java

public class LazyAdapter extends BaseAdapter { 

    private Activity activity; 
    private ArrayList<HashMap<String, String>> data=new ArrayList<HashMap<String, String>>(); 
    private static LayoutInflater inflater=null; 
    public ImageLoader imageLoader; 


    public static HashMap<String, String> song; 

    public LazyAdapter(Activity a, ArrayList<HashMap<String, String>> d) { 
     activity = a; 
     data=d; 
     inflater = (LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
     imageLoader=new ImageLoader(activity.getApplicationContext()); 
    } 

    public int getCount() { 
     return data.size(); 
    } 

    public Object getItem(int position) { 
     return position; 
    } 

    public long getItemId(int position) { 
     return position; 
    } 

    public View getView(int position, View convertView, ViewGroup parent) { 
     View vi=convertView; 
     if(convertView==null) 
      vi = inflater.inflate(R.layout.list_row, null); 

     TextView title = (TextView)vi.findViewById(R.id.title); // title 
     TextView artist = (TextView)vi.findViewById(R.id.artist); // artist name 
     TextView duration = (TextView)vi.findViewById(R.id.duration); // duration 
     ImageView thumb_image=(ImageView)vi.findViewById(R.id.list_image); // thumb image 

     song = new HashMap<String, String>(); 
     song = data.get(position); 

     // Setting all values in listview 
     title.setText(song.get(CustomizedListView.KEY_TITLE)); 
     artist.setText(song.get(CustomizedListView.KEY_ARTIST)); 
     duration.setText(song.get(CustomizedListView.KEY_DURATION)); 
     imageLoader.DisplayImage(song.get(CustomizedListView.KEY_THUMB_URL), thumb_image); 
     return vi; 
    } 
} 

Answer 1

在您自定义适配器要返回的位置，而不是项目

public Object getItem(int position) { 
      return position; 
     } 

尝试使用这种

public Object getItem(int position) { 
       return data.get(position); 
      } 

这将解决您的问题