在Eclipse IDE中了解Log Cat错误

Question

我正在制作一个android应用程序，每次我尝试运行我的应用程序时都会出现一些错误。

我已经阅读了一些关于Java中的空指针异常的资料，但实际上无法实现任何解决方案。

看来我的代码中有一个错误，我需要纠正。

供您参考，我收到以下错误在我的日志：

03-07 18:42:27.562: W/dalvikvm(631): threadid=1: thread exiting with uncaught exception (group=0x40014760) 
03-07 18:42:27.582: E/AndroidRuntime(631): FATAL EXCEPTION: main 
03-07 18:42:27.582: E/AndroidRuntime(631): java.lang.NullPointerException 
03-07 18:42:27.582: E/AndroidRuntime(631): at com.fokrul.justdeals.ActivityTab$BooksAdapter.getView(ActivityTab.java:1453) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.widget.AbsListView.obtainView(AbsListView.java:1970) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.widget.ListView.makeAndAddView(ListView.java:1756) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.widget.ListView.fillDown(ListView.java:656) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.widget.ListView.fillFromTop(ListView.java:716) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.widget.ListView.layoutChildren(ListView.java:1595) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.widget.AbsListView.onLayout(AbsListView.java:1800) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.view.View.layout(View.java:9581) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.view.ViewGroup.layout(ViewGroup.java:3877) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.widget.RelativeLayout.onLayout(RelativeLayout.java:912) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.view.View.layout(View.java:9581) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.view.ViewGroup.layout(ViewGroup.java:3877) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.widget.FrameLayout.onLayout(FrameLayout.java:400) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.view.View.layout(View.java:9581) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.view.ViewGroup.layout(ViewGroup.java:3877) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1542) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1403) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.widget.LinearLayout.onLayout(LinearLayout.java:1314) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.view.View.layout(View.java:9581) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.view.ViewGroup.layout(ViewGroup.java:3877) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.widget.FrameLayout.onLayout(FrameLayout.java:400) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.view.View.layout(View.java:9581) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.view.ViewGroup.layout(ViewGroup.java:3877) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.widget.RelativeLayout.onLayout(RelativeLayout.java:912) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.view.View.layout(View.java:9581) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.view.ViewGroup.layout(ViewGroup.java:3877) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.widget.FrameLayout.onLayout(FrameLayout.java:400) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.view.View.layout(View.java:9581) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.view.ViewGroup.layout(ViewGroup.java:3877) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1542) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1403) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.widget.LinearLayout.onLayout(LinearLayout.java:1314) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.view.View.layout(View.java:9581) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.view.ViewGroup.layout(ViewGroup.java:3877) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.widget.FrameLayout.onLayout(FrameLayout.java:400) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.view.View.layout(View.java:9581) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.view.ViewGroup.layout(ViewGroup.java:3877) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.view.ViewRoot.performTraversals(ViewRoot.java:1282) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.view.ViewRoot.handleMessage(ViewRoot.java:2040) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.os.Handler.dispatchMessage(Handler.java:99) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.os.Looper.loop(Looper.java:132) 
03-07 18:42:27.582: E/AndroidRuntime(631): at android.app.ActivityThread.main(ActivityThread.java:4123) 
03-07 18:42:27.582: E/AndroidRuntime(631): at java.lang.reflect.Method.invokeNative(Native Method) 
03-07 18:42:27.582: E/AndroidRuntime(631): at java.lang.reflect.Method.invoke(Method.java:491) 
03-07 18:42:27.582: E/AndroidRuntime(631): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841) 
03-07 18:42:27.582: E/AndroidRuntime(631): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599) 
03-07 18:42:27.582: E/AndroidRuntime(631): at dalvik.system.NativeStart.main(Native Method) 

我不能找出真正的问题是什么！任何想法这些错误可能指向什么？

您的帮助将不胜感激。先谢谢你。

编辑：1个ACTIVITYTAB.JAVA

// to get a View that displays the data at the specified position in the data set. 
     public View getView(int position, View convertView, ViewGroup parent) { 
      PromotionsHolder holder; 
      if(convertView == null){ 
       convertView = inflater.inflate(R.layout.item_product, null); 
       holder = new PromotionsHolder(); 
       holder.imgImage = (ImageView)convertView.findViewById(R.id.imgImage); 
       holder.imgImage.getLayoutParams().height = 80; 
       holder.imgImage.getLayoutParams().width = 80; 
       holder.tvName = (TextView)convertView.findViewById(R.id.tvName); 
       holder.tvTitle = (TextView)convertView.findViewById(R.id.tvTitle); 
       holder.tvPrice = (TextView)convertView.findViewById(R.id.tvPrice); 
       convertView.setTag(holder); 
      }else{ 
       holder = (PromotionsHolder)convertView.getTag(); 
      } 
      Bitmap bmp = BitmapFactory.decodeFile(soImage.get(position)); 
      holder.imgImage.setImageBitmap(bmp); 
      holder.tvTitle.setText(soTitle.get(position)); 
      ((TextView) holder.tvCode).setText(soCode.get(position)); 
      holder.tvPrice.setText(soPrice.get(position)); 

      return convertView; 
     } 
    } 

    private static class ProductsHolder{ 
     ImageView imgImage; 
     TextView tvCode, tvPrice, tvTitle; 
    } 

    private class BooksAdapter extends BaseAdapter{ 
     private LayoutInflater inflater; 
     private ArrayList<String> list; 

     public BooksAdapter(ArrayList<String> ll){ 
      inflater = (LayoutInflater)ActivityTab.this.getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
      list = ll; 
     } 

     //number of items in the data set are linked by this Adapter. 
     public int getCount() { 
      return list.size(); 
     } 

     // to get data item associated with the specified position in the data set. 
     public Object getItem(int position) { 
      return list.get(position); 
     } 

     // to get the row id associated with the specified position in the list. 
     public long getItemId(int position) { 
      return position; 
     } 

     // to get a View that displays the data at the specified position in the data set. 
     public View getView(int position, View convertView, ViewGroup parent) { 
      ProductsHolder holder; 
      if(convertView == null){ 
       convertView = inflater.inflate(R.layout.item_product, null); 
       holder = new ProductsHolder(); 
       holder.imgImage = (ImageView)convertView.findViewById(R.id.imgImage); 
       holder.imgImage.getLayoutParams().height = 80; 
       holder.imgImage.getLayoutParams().width = 80; 
       holder.tvCode = (TextView)convertView.findViewById(R.id.tvCode); 
       holder.tvTitle = (TextView)convertView.findViewById(R.id.tvTitle); 
       holder.tvPrice = (TextView)convertView.findViewById(R.id.tvPrice); 
       convertView.setTag(holder); 
      }else{ 
       holder = (ProductsHolder)convertView.getTag(); 
      } 
      Bitmap bmp = BitmapFactory.decodeFile(bImage.get(position)); 
      holder.imgImage.setImageBitmap(bmp); 
      holder.tvTitle.setText(bTitle.get(position)); <----Line 1453 
      holder.tvCode.setText(bCode.get(position));  
      holder.tvPrice.setText(bPrice.get(position)); 

      return convertView; 
     } 
    } 

Answer 1

原因NullPointerException异常

它发生时，任何对象包含空和你正在试图访问它。

例如，

String str = null; 
Log.v("App",str); 

检查ActivityTab.java:1453。在这种情况下，它发生在这条线上。