通過ArrayAdapter將ImageView添加到列表視圖項目

我想以編程方式添加多個圖像視圖，這取決於是否有圖像可以查看或不是。所以我在我的ArrayAdapter類中試過這個..我在這裏做的是檢查是否有額外的圖像的任何URL或沒有，然後創建一個數的ImageView的在其上顯示這些圖像通過ArrayAdapter將ImageView添加到列表視圖項目

@Override 
public View getView(int position, View rowView, ViewGroup parent) { 
    // TODO Auto-generated method stub 
    HeaderHolder headerRow = null; 
    View hs = null; 
    if (position == 0) { 
     if (hs == null) { 
      LayoutInflater inflater = (LayoutInflater) getContext() 
        .getSystemService(Context.LAYOUT_INFLATER_SERVICE); 

      rowView = inflater.inflate(R.layout.header, null); 
      LinearLayout linear =(LinearLayout) rowView.findViewById(R.id.headerlayout); 

      TextView main = (TextView) rowView.findViewById(R.id.headLine); 
      main.setText(appManager.getDetails().getTitle()); 
      // Log.d("display width ", "" + display.getWidth()); 

      // TextViewJustify.justifyText(main, display.getWidth() - 400f 
      //); 
      TextView pubDate = (TextView) rowView 
        .findViewById(R.id.pubdate); 
      pubDate.setText(appManager.getDetails().getPubDate()); 
      TextView detailsBody = (TextView) rowView 
        .findViewById(R.id.detailsBody); 

      detailsBody.setText(appManager.getDetails().getBody()); 
      // TextViewJustify.justifyText(detailsBody, display.getWidth() - 
      // 400f); 
      ImageView iv = (ImageView) rowView.findViewById(R.id.main); 
      String url = appManager.getDetails().getMainImageLink(); 
      if (url != null) { 

       loader.fetchDrawableOnThread(appManager.getDetails() 
         .getMainImageLink(), iv); 

      } 

      if (appManager.getDetails().images.size() > 0) { 


       for (int i = 0; i < appManager.getDetails().images.size(); i++) { 
        im[i]= new ImageView(context); 
        im[i].setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT)); 
        im[i].setScaleType(ScaleType.FIT_XY); 
        linear.addView(im[i]); 
        loader.fetchDrawableOnThread(appManager.getDetails().images.get(i), im[i]); 
       } 
      } 



      ImageView play = (ImageView) rowView 
        .findViewById(R.id.videoYoutube); 
      if (appManager.getDetails().getVideos().size() > 0) { 
       play.setVisibility(View.VISIBLE); 
       play.setOnClickListener(new OnClickListener() { 

        public void onClick(View arg0) { 
         // TODO Auto-generated method stub 
         context.startActivity(new Intent(
           Intent.ACTION_VIEW, Uri.parse(appManager 
             .getDetails().getVideos().get(0)))); 
        } 
       }); 
      } 

      headerRow = new HeaderHolder(); 
      headerRow.headLine = main; 
      headerRow.pubDate = pubDate; 
      headerRow.main = iv; 
      headerRow.lin = linear; 
      headerRow.details_images = im ; 
      headerRow.playButton = play; 
      hs = rowView; 
      hs.setTag(headerRow); 
     } 


    } 

    else if (position >= 1) { 

     .............. 

    } 

    return rowView; 
}

它總是給我的錯誤在im[i]= new ImageView(context);我不知道爲什麼！

我的錯誤日誌

06-26 12:21:49.064: E/AndroidRuntime(2806): FATAL EXCEPTION: main 
    06-26 12:21:49.064: E/AndroidRuntime(2806): java.lang.NullPointerException 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at  com.nazzelha.youm7.DetailsAdapter.getView(DetailsAdapter.java:111) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.widget.HeaderViewListAdapter.getView(HeaderViewListAdapter.java:220) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.widget.AbsListView.obtainView(AbsListView.java:2159) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.widget.ListView.makeAndAddView(ListView.java:1831) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.widget.ListView.fillDown(ListView.java:674) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.widget.ListView.fillFromTop(ListView.java:735) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.widget.ListView.layoutChildren(ListView.java:1652) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.widget.AbsListView.onLayout(AbsListView.java:1994) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.view.View.layout(View.java:14008) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.view.ViewGroup.layout(ViewGroup.java:4373) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1021) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.view.View.layout(View.java:14008) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.view.ViewGroup.layout(ViewGroup.java:4373) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.widget.FrameLayout.onLayout(FrameLayout.java:448) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.view.View.layout(View.java:14008) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.view.ViewGroup.layout(ViewGroup.java:4373) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1663) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1521) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.widget.LinearLayout.onLayout(LinearLayout.java:1434) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.view.View.layout(View.java:14008) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.view.ViewGroup.layout(ViewGroup.java:4373) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.widget.FrameLayout.onLayout(FrameLayout.java:448) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.view.View.layout(View.java:14008) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.view.ViewGroup.layout(ViewGroup.java:4373) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:1892) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1711) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:989) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4351) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.view.Choreographer.doCallbacks(Choreographer.java:562) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.view.Choreographer.doFrame(Choreographer.java:532) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.os.Handler.handleCallback(Handler.java:725) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.os.Handler.dispatchMessage(Handler.java:92) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.os.Looper.loop(Looper.java:137) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at android.app.ActivityThread.main(ActivityThread.java:5041) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at java.lang.reflect.Method.invokeNative(Native Method) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at java.lang.reflect.Method.invoke(Method.java:511) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 
    06-26 12:21:49.064: E/AndroidRuntime(2806): at dalvik.system.NativeStart.main(Native Method)

來源

2013-06-26 vezikon

什麼樣的錯誤，它給你的對象數組？你有沒有指定你的IM數組的長度？ –

檢查你的logcat並告訴我們你得到的錯誤。而且錯誤可能是存在的，你不把上下文值放到上下文變量中。將上下文初始化爲類變量。在構造函數中放入this.context = context;不管它的第一個參數是什麼 – Android

我從適配器的構造函數中獲取上下文，所以 – vezikon

這意味着你可能忘了初始化IM（ImageView的）陣列，它應該這樣做：

ImageView [ ] im = new ImageView [ 3 ]; 
im[0] = new ImageView(context); //filling one element at a time 
temps[1] = ..; 
temps[2] = ..;

或循環使用：

for(int imgNr = 0; imgNr < 3; imgNr++) { //fill one element at a time im[imgNr] = new ImageView(context); }

或使用任何其他已知方法進行初始化並填充對象數組。

你必須這樣做，因爲數組的大小總是固定在Java中。通常不是使用數組，而是使用List的實現或任何其他替代方法，這不需要大小定義。

如果以後在應用程序所需的陣列，指定者方法可用於檢索居住在列表

來源

2013-06-26 11:21:39

通過ArrayAdapter將ImageView添加到列表視圖項目

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