Android：具有兩種不同視圖的EfficientAdapter

我使用基於SDK演示示例中的EfficientAdapter example的BaseAdapter擴展版本。Android：具有兩種不同視圖的EfficientAdapter

我的數據基本上是一個對象（ListPlaces），它包含一個ArrayList以及實際的位置列表，可通過listPlaces.getValues()訪問。此ArrayList數據按範圍排序，ArrayList由一些特殊項目（分隔符）組成，但沒有數據，但separator標誌設置爲true。

現在，每當我EfficientAdapter得到一個數據對象，它是返回false爲public boolean isEnabled(int position)和public View getView(int position, View convertView, ViewGroup parent)依靠，如果當前數據對象包括實時數據或只是一個分隔符虛擬膨脹兩種不同佈局的分隔符。

這很好，如果我每次膨脹佈局。但是，每次膨脹佈局並呼籲findViewById使得ListView幾乎非常慢。

所以我試着用ViewHolder的方法使用EfficientAdapter。但是，由於我嘗試訪問兩種不同的觀點，這並不適用於開箱即用。因此，只要我的convertView != null（其他情況）通過我們的ViewHolder訪問佈局上的項目，並且當前一個View是分隔符時，它當然無法訪問僅在「真實」項目佈局上可用的TextView 。

所以我還逼我getView()膨脹佈局不僅當convertView == null，還當上一listRow比當前的一個不同：if (convertView == null || (listRow != listRow_previous)) { [....] }

這似乎幾乎現在的工作。或者至少它從一開始就不會崩潰。但它仍然崩潰，我不知道我要做什麼不同。我試圖去查看convertView.getID()和convertView.getResources()，但到目前爲止這並沒有真正的幫助。也許別人有一個想法，我可以檢查我的當前convertView是否與列表項目佈局或列表分隔符佈局匹配。謝謝。

這是代碼。凡曾經有一個[...]我拿出一些不太重要的代碼，使其更容易閱讀和理解：

private class EfficientAdapter extends BaseAdapter { 
    private LayoutInflater mInflater; 
    private ListPlaces listPlaces; 

    private ListRow listRow; 
    private ListRow listRow_previous; 


    public EfficientAdapter(Context context, ListPlaces listPlaces) { 
     // Cache the LayoutInflate to avoid asking for a new one each time. 
     mInflater = LayoutInflater.from(context); 

     // Data 
     this.listPlaces = listPlaces; 
    } 

    /** 
    * The number of items in the list is determined by the number of items 
    * in our ArrayList 
    * 
    * @see android.widget.ListAdapter#getCount() 
    */ 
    public int getCount() { 
     return listPlaces.getValues().size(); 
    } 

    /** 
    * Since the data comes from an array, just returning the index is 
    * sufficent to get at the data. If we were using a more complex data 
    * structure, we would return whatever object represents one row in the 
    * list. 
    * 
    * @see android.widget.ListAdapter#getItem(int) 
    */ 
    public Object getItem(int position) { 
     return position; 
    } 

    /** 
    * Use the array index as a unique id. 
    * 
    * @see android.widget.ListAdapter#getItemId(int) 
    */ 
    public long getItemId(int position) { 
     return position; 
    } 

    @Override 
    public boolean isEnabled(int position) { 
     // return false if item is a separator: 
     if(listPlaces.getValues().get(position).separator >= 0) 
      return false; 
     else 
      return true; 
    } 

    @Override 
    public boolean areAllItemsEnabled() { 
     return false;   
    } 



    /** 
    * Make a view to hold each row. 
    * 
    * @see android.widget.ListAdapter#getView(int, android.view.View, 
    *  android.view.ViewGroup) 
    */ 
    public View getView(int position, View convertView, ViewGroup parent) { 

     // Get the values for the current list element 
     ListPlacesValues curValues = listPlaces.getValues().get(position); 
     if (curValues.separator >= 0) 
      listRow = ListRow.SEPARATOR; 
     else 
      listRow = ListRow.ITEM; 
     Log.i(TAG,"Adapter: getView("+position+") " + listRow + " (" + listRow_previous + ") -> START"); 

     // A ViewHolder keeps references to children views to avoid unneccessary calls 
     // to findViewById() on each row. 
     ViewHolder holder; 

     // When convertView is not null, we can reuse it directly, there is no need 
     // to reinflate it. We only inflate a new View when the convertView supplied 
     // by ListView is null. 
     if (convertView == null || (listRow != listRow_previous)) { 
      Log.i(TAG, "--> (convertView == null) at position: " + position); 
      // Creates a ViewHolder and store references to the two children views 
      // we want to bind data to. 
      holder = new ViewHolder(); 

      if (listRow == ListRow.SEPARATOR) { 
       convertView = mInflater.inflate(R.layout.taxonomy_list_separator, null); 
       holder.separatorText = (TextView) convertView.findViewById(R.id.separatorText); 
       convertView.setTag(holder); 
       Log.i(TAG,"\tCREATE SEPARATOR: convertView ID: " + convertView.getId() + " Resource: " + convertView.getResources()); 

      } 
      else { 

       convertView = mInflater.inflate(R.layout.taxonomy_listitem, null); 
       holder.name = (TextView) convertView.findViewById(R.id.name); 
       holder.category = (TextView) convertView.findViewById(R.id.category); 
       // [...] 

       convertView.setTag(holder); 

       Log.i(TAG,"\tCREATE ITEM: convertView ID: " + convertView.getId() + " Resource: " + convertView.getResources()); 
      } 
     } else { 
      // Get the ViewHolder back to get fast access to the TextView 
      // and the ImageView. 
      Log.i(TAG,"\tconvertView ID: " + convertView.getId() + " Resource: " + convertView.getResources()); 

      holder = (ViewHolder) convertView.getTag(); 
      convertView.setAnimation(null); 
     } 

     /* Bind the data efficiently with the holder */ 
     if (listRow == ListRow.SEPARATOR) { 
      String separatorText; 
      switch (curValues.separator) { 
      case 0: separatorText="case 0"; break; 
      case 1: separatorText="case 1"; break; 
      case 2: separatorText="case 2"; break; 
      // [...] 
     default: separatorText="[ERROR]"; break; 
      } 
      holder.separatorText.setText(separatorText); 
     } 
     else { 
      // Set the name: 
      holder.name.setText(curValues.name); 
      // Set category 
      String cat = curValues.classification.toString(); 
      cat = cat.substring(1,cat.length()-1); // removing "[" and "]" 
      if (cat.length() > 35) { 
       cat = cat.substring(0, 35); 
       cat = cat + "..."; 
      } 
      holder.category.setText(cat); 

      // [...] (and many more TextViews and ImageViews to be set) 

     } 

     listRow_previous = listRow; 
     Log.i(TAG,"Adapter: getView("+position+") -> DONE"); 
     return convertView; 
    } 

    private class ViewHolder { 
     TextView name; 
     TextView category; 
     // [...] -> many more TextViews and ImageViews 

     TextView separatorText; 
    } 
}

在這裏，我logcat的輸出：

755  ListPlaces_Activity I onPostExecute: notifyDataSetChanged()                         
    755  ListPlaces_Activity I Adapter: getView(0) SEPARATOR (null) -> START                       
    755  ListPlaces_Activity I --> (convertView == null) at position: 0                        
    755  ListPlaces_Activity I  CREATE SEPARATOR: convertView ID: 2131296317 Resource: [email protected]         
    755  ListPlaces_Activity I Adapter: getView(0) -> DONE                           
    755  ListPlaces_Activity I Adapter: getView(1) ITEM (SEPARATOR) -> START                       
    755  ListPlaces_Activity I --> (convertView == null) at position: 1                        
    755  ListPlaces_Activity I  CREATE ITEM: convertView ID: 2131296317 Resource: [email protected]          
    755  ListPlaces_Activity I Adapter: getView(1) -> DONE                           
    755  ListPlaces_Activity I Adapter: getView(2) SEPARATOR (ITEM) -> START                       
    755  ListPlaces_Activity I --> (convertView == null) at position: 2                        
    755  ListPlaces_Activity I  CREATE SEPARATOR: convertView ID: 2131296317 Resource: [email protected]         
    755  ListPlaces_Activity I Adapter: getView(2) -> DONE                           
    755  ListPlaces_Activity I Adapter: getView(3) ITEM (SEPARATOR) -> START                       
    755  ListPlaces_Activity I --> (convertView == null) at position: 3                        
    755  ListPlaces_Activity I  CREATE ITEM: convertView ID: 2131296317 Resource: android.content.res.R[email protected]          
    755  ListPlaces_Activity I Adapter: getView(3) -> DONE                           
    755  ListPlaces_Activity I Adapter: getView(4) ITEM (ITEM) -> START                        
    755  ListPlaces_Activity I  convertView ID: 2131296317 Resource: [email protected]              
    755  ListPlaces_Activity I Adapter: getView(4) -> DONE                           
    755  ListPlaces_Activity I Adapter: getView(5) ITEM (ITEM) -> START                        
    755  ListPlaces_Activity I  convertView ID: 2131296317 Resource: [email protected]              
    755  ListPlaces_Activity I Adapter: getView(5) -> DONE                           
    755  ListPlaces_Activity I Adapter: getView(6) ITEM (ITEM) -> START                        
    755  ListPlaces_Activity I  convertView ID: 2131296317 Resource: [email protected]              
    755  ListPlaces_Activity I Adapter: getView(6) -> DONE                           
    755  ListPlaces_Activity I Adapter: getView(0) SEPARATOR (ITEM) -> START                       
    755  ListPlaces_Activity I --> (convertView == null) at position: 0                        
    755  ListPlaces_Activity I  CREATE SEPARATOR: convertView ID: 2131296317 Resource: [email protected]         
    755  ListPlaces_Activity I Adapter: getView(0) -> DONE                           
    755  ListPlaces_Activity I Adapter: getView(1) ITEM (SEPARATOR) -> START                       
    755  ListPlaces_Activity I --> (convertView == null) at position: 1                        
    755  ListPlaces_Activity I  CREATE ITEM: convertView ID: 2131296317 Resource: [email protected]          
    755  ListPlaces_Activity I Adapter: getView(1) -> DONE                           
    755  ListPlaces_Activity I Adapter: getView(2) SEPARATOR (ITEM) -> START                       
    755  ListPlaces_Activity I --> (convertView == null) at position: 2                        
    755  ListPlaces_Activity I  CREATE SEPARATOR: convertView ID: 2131296317 Resource: [email protected]         
    755  ListPlaces_Activity I Adapter: getView(2) -> DONE                           
    755  ListPlaces_Activity I Adapter: getView(3) ITEM (SEPARATOR) -> START                       
    755  ListPlaces_Activity I --> (convertView == null) at position: 3                        
    755  ListPlaces_Activity I  CREATE ITEM: convertView ID: 2131296317 Resource: [email protected]          
    755  ListPlaces_Activity I Adapter: getView(3) -> DONE                           
    755  ListPlaces_Activity I Adapter: getView(4) ITEM (ITEM) -> START                        
    755  ListPlaces_Activity I  convertView ID: 2131296317 Resource: [email protected]              
    755  ListPlaces_Activity I Adapter: getView(4) -> DONE                           
    755  ListPlaces_Activity I Adapter: getView(5) ITEM (ITEM) -> START                        
    755  ListPlaces_Activity I  convertView ID: 2131296317 Resource: [email protected]              
    755   AndroidRuntime D Shutting down VM                              
    755    dalvikvm W threadid=3: thread exiting with uncaught exception (group=0x4001aa28)                 
    755   AndroidRuntime E Uncaught handler: thread main exiting due to uncaught exception                  
    755   AndroidRuntime E java.lang.NullPointerException                          
    755   AndroidRuntime E  at com.tato.main.ListPlaces_Activity$EfficientAdapter.getView(ListPlaces_Activity.java:330)          
    755   AndroidRuntime E  at android.widget.HeaderViewListAdapter.getView(HeaderViewListAdapter.java:191)             
    755   AndroidRuntime E  at android.widget.AbsListView.obtainView(AbsListView.java:1255)                 
    755   AndroidRuntime E  at android.widget.ListView.makeAndAddView(ListView.java:1658)                 
    755   AndroidRuntime E  at android.widget.ListView.fillDown(ListView.java:637)                   
    755   AndroidRuntime E  at android.widget.ListView.fillFromTop(ListView.java:694)                  
    755   AndroidRuntime E  at android.widget.ListView.layoutChildren(ListView.java:1502)                 
    755   AndroidRuntime E  at android.widget.AbsListView.onLayout(AbsListView.java:1112)                 
    755   AndroidRuntime E  at android.view.View.layout(View.java:6569)                      
    755   AndroidRuntime E  at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1119)               
    755   AndroidRuntime E  at android.widget.LinearLayout.layoutVertical(LinearLayout.java:998)               
    755   AndroidRuntime E  at android.widget.LinearLayout.onLayout(LinearLayout.java:918)                 
    755   AndroidRuntime E  at android.view.View.layout(View.java:6569)                      
    755   AndroidRuntime E  at android.widget.FrameLayout.onLayout(FrameLayout.java:333)                 
    755   AndroidRuntime E  at android.view.View.layout(View.java:6569)                      
    755   AndroidRuntime E  at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1119)               
    755   AndroidRuntime E  at android.widget.LinearLayout.layoutVertical(LinearLayout.java:998)               
    755   AndroidRuntime E  at android.widget.LinearLayout.onLayout(LinearLayout.java:918)                 
    755   AndroidRuntime E  at android.view.View.layout(View.java:6569)                      
    755   AndroidRuntime E  at android.widget.FrameLayout.onLayout(FrameLayout.java:333)                 
    755   AndroidRuntime E  at android.view.View.layout(View.java:6569)                      
    755   AndroidRuntime E  at android.view.ViewRoot.performTraversals(ViewRoot.java:979)                 
    755   AndroidRuntime E  at android.view.ViewRoot.handleMessage(ViewRoot.java:1613)                  
    755   AndroidRuntime E  at android.os.Handler.dispatchMessage(Handler.java:99)                   
    755   AndroidRuntime E  at android.os.Looper.loop(Looper.java:123)                      
    755   AndroidRuntime E  at android.app.ActivityThread.main(ActivityThread.java:4203)                 
    755   AndroidRuntime E  at java.lang.reflect.Method.invokeNative(Native Method)                   
    755   AndroidRuntime E  at java.lang.reflect.Method.invoke(Method.java:521)                    
    755   AndroidRuntime E  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791)            
    755   AndroidRuntime E  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:549)                 
    755   AndroidRuntime E  at dalvik.system.NativeStart.main(Native Method)

來源

2009-11-02 znq

你可以添加一個註釋來顯示堆棧跟蹤中的行300是哪裏嗎？如果它是'if（curValues.separator> = 0）'，你應該能夠在列表的最後處理多達1的位置嗎？ – rsp 2009-11-02 10:41:29

你忘了有幾種方法需要覆蓋：getViewTypeCount()和getItemViewType()。對於所有行都相同的列表，這些不是必需的，但它們對於您的方案非常重要。正確實施這些，Android將爲您的標題和詳細信息行維護單獨的對象池。

或者，你可以看看：

傑夫·夏基的原始SeparatedListAdapter（GPL）
我updated rendition（GPL）
我MergeAdapter，其可用於這種情況下，以及（阿帕奇）

來源

2009-11-02 13:51:50 CommonsWare

感謝您的快速響應。提示getViewTypeCount（）和getItemViewType（）非常有用。我喜歡這個適配器的東西。也感謝您分享您和Jeff Sharkey的源代碼。我上週已經看過它，但是由於我目前正在開發一個封閉源代碼項目，所以我至少不能實現GPL示例。所以我決定開始自己的實施，現在終於有效了，這要感謝您的幫助。 Muchas格拉西亞斯！ – znq 2009-11-02 14:52:03

更新的演繹鏈接不再工作。找不到仍然有效的鏈接 – rtack 2014-09-10 06:36:54

感謝getViewTypeCount（）和getItemViewType（）的提示，它現在可以很好地工作。

這兩種方法實現是非常簡單的：

@Override 
public int getViewTypeCount() { 
    return 2; 
} 

@Override 
public int getItemViewType(int position) { 
if(listPlaces.getValues().get(position).separator >= 0) 
    return 0; 
else 
    return 1; 
}

由於commonsware在他的回答這樣Android將保持不同的列表項，這也意味着你可以刪除檢查listRow_previous不同的對象池提到在我的示例中，只將if (convertView == null || (listRow != listRow_previous))更改爲if (convertView == null)。

來源

2009-11-02 15:01:46 znq

Android：具有兩種不同視圖的EfficientAdapter

回答

相關問題