ViewHolder не работает

Question

Я следил за этим уроком http://xjaphx.wordpress.com/2011/06/16/viewholder-pattern-caching-view-efficiently/. однако он не работает. Можете ли вы, ребята, помочь мне, как это сделать?

class Custom extends Activity { 

private ListView listview; 
private ArrayList mListItem; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
     setContentView(R.layout.custom); 

    listview = (ListView) findViewById(R.id.list_view); 
    mListItem = ItemsDisplay.getItems(true); 

    listview.setAdapter(new CustomListAdapter(this, R.id.list_view,mListItem)); 
} 

static class ViewHolder { 
     public TextView textView; 
    } 

    private class CustomListAdapter extends ArrayAdapter { 
     private ArrayList mList; //--CloneChangeRequired 
     private Context mContext; 

     public CustomListAdapter(Context context, int textViewResourceId, 
       ArrayList list) { //--CloneChangeRequired 
      super(context, textViewResourceId, list); 
      this.mList = list; 
      this.mContext = context; 
     } 

     public View getView(int position, View convertView, ViewGroup parent) { 
      View view = convertView; 

      final ToggleButton tb; 

      System.out.println("position "+position+" mList.size"+mList.size()); 
      if (view == null) { 

       LayoutInflater vi = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
       view = vi.inflate(R.layout.list_item_bn, null); 
       ViewHolder holder = new ViewHolder(); 
       holder.textView = (TextView)convertView.findViewById(R.id.tv_name); 
       view.setTag(holder); 
      } 

      ItemsDisplay listItem = (ItemsDisplay) mList.get(position); 
      System.out.println("listItem.getName() " +listItem.getName()); 
       if (listItem != null) { 

       ViewHolder holder1 = (ViewHolder)view.getTag(); 
       holder1.textView.setText(listItem.getName()); 

       } 

      return view; 
     } 

    } 
} 

Я уже изучал эти сообщения, но я не уверен, почему мой код все еще не работает. How to implement a view holder? ListView with ArrayAdapter and ViewHolder adding icons to the wrong item

Answer 1

изменения:

 final ToggleButton tb; 

     System.out.println("position "+position+" mList.size"+mList.size()); 
     if (convertView == null) { 

      LayoutInflater vi = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
      convertView = vi.inflate(R.layout.list_item_bn, null); 
      ViewHolder holder = new ViewHolder(); 
      holder.textView = (TextView)convertView.findViewById(R.id.tv_name); 
      convertView.setTag(holder); 
     } 

     ItemsDisplay listItem = (ItemsDisplay) mList.get(position); 
     System.out.println("listItem.getName() " +listItem.getName()); 
      if (listItem != null) { 

      ViewHolder holder1 = (ViewHolder)convertView.getTag(); 
      holder1.textView.setText(listItem.getName()); 

      } 

     return convertView; 

Answer 2

Попробуйте это:

public View getView(int position, View convertView, ViewGroup parent) { 
    View view = convertView; 
    ViewHolder holder; 
    final ToggleButton tb; 
    System.out.println("position "+position+" mList.size"+mList.size()); 
    if (view == null) { 
     LayoutInflater vi = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
     view = vi.inflate(R.layout.list_item_bn, null); 
     holder = new ViewHolder(); 
     holder.textView = (TextView)view.findViewById(R.id.tv_name); 
     view.setTag(holder); 
      } 
      else { 
       holder = (ViewHolder)view.getTag(); 
      } 
    ItemsDisplay listItem = (ItemsDisplay) mList.get(position); 
    System.out.println("listItem.getName() " +listItem.getName()); 
    if (listItem != null) { 
     holder.textView.setText(listItem.getName()); 
     } 
     return view; 
    } 

Answer 3

Надеется, что это работает: - Решения: вы должны SetTag() в "если" состоянии и GetTag() в части «else».

 public View getView(int position, View convertView, ViewGroup parent) { 
     View view = convertView; 
     ViewHolder holder ; 
     final ToggleButton tb; 

     System.out.println("position "+position+" mList.size"+mList.size()); 
     if (view == null) { 
      holder = new ViewHolder(); 
      LayoutInflater vi = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
      view = vi.inflate(R.layout.list_item_bn, null); 

      holder.textView = (TextView)convertView.findViewById(R.id.tv_name); 
      view.setTag(holder); 
     } 
     else{ 
      holder = (ViewHolder)view.getTag(); 
     } 
     //set the list data here.. 
     ItemsDisplay listItem = (ItemsDisplay) mList.get(position); 

     holder1.textView.setText(listItem.getName()); 



     return view; 
    }