Android的自定义适配器getView（）NullPointerException异常突然冒出​​来！ [英] Android custom adapter getView() NullPointerException out of nowhere!

问题描述

我有一个自定义的适配器为ListView控件提供数据。一切运行良好，但'突然'（我没有什么现在发生的另一种说法），我的应用程序启动而载入我的活动与列表视图崩溃：

I've got a custom Adapter to supply data for ListView. Everything worked fine, but 'suddenly'(I don't have another word for what's now happening) my app started crashing while loading my Activity with listview:

W/dalvikvm(  228): threadid=3: thread exiting with uncaught exception (group=0x4001b188)

E/AndroidRuntime(  228): Uncaught handler: thread main exiting due to uncaught exception

E/AndroidRuntime(  228): java.lang.NullPointerException

E/AndroidRuntime(  228):    at AdvertisementListAdapter.getView(AdvertisementListAdapter.java:72)

E/AndroidRuntime(  228):    at android.widget.AbsListView.obtainView(AbsListView.java:1274)

E/AndroidRuntime(  228):    at android.widget.ListView.measureHeightOfChildren(ListView.java:1147)

E/AndroidRuntime(  228):    at android.widget.ListView.onMeasure(ListView.java:1060)

E/AndroidRuntime(  228):    at android.view.View.measure(View.java:7964)

E/AndroidRuntime(  228):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3023)

E/AndroidRuntime(  228):    at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:888)

E/AndroidRuntime(  228):    at android.widget.LinearLayout.measureVertical(LinearLayout.java:350)

E/AndroidRuntime(  228):    at android.widget.LinearLayout.onMeasure(LinearLayout.java:278)

E/AndroidRuntime(  228):    at android.view.View.measure(View.java:7964)

E/AndroidRuntime(  228):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3023)

E/AndroidRuntime(  228):    at android.widget.FrameLayout.onMeasure(FrameLayout.java:245)

E/AndroidRuntime(  228):    at android.view.View.measure(View.java:7964)

E/AndroidRuntime(  228):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3023)

E/AndroidRuntime(  228):    at android.widget.FrameLayout.onMeasure(FrameLayout.java:245)

E/AndroidRuntime(  228):    at android.view.View.measure(View.java:7964)

E/AndroidRuntime(  228):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3023)

E/AndroidRuntime(  228):    at android.widget.FrameLayout.onMeasure(FrameLayout.java:245)

E/AndroidRuntime(  228):    at android.view.View.measure(View.java:7964)

E/AndroidRuntime(  228):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3023)

E/AndroidRuntime(  228):    at android.widget.FrameLayout.onMeasure(FrameLayout.java:245)

E/AndroidRuntime(  228):    at android.view.View.measure(View.java:7964)

E/AndroidRuntime(  228):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3023)

E/AndroidRuntime(  228):    at android.widget.FrameLayout.onMeasure(FrameLayout.java:245)

E/AndroidRuntime(  228):    at android.view.View.measure(View.java:7964)

E/AndroidRuntime(  228):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3023)

E/AndroidRuntime(  228):    at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:888)

E/AndroidRuntime(  228):    at android.widget.LinearLayout.measureVertical(LinearLayout.java:350)

E/AndroidRuntime(  228):    at android.widget.LinearLayout.onMeasure(LinearLayout.java:278)

E/AndroidRuntime(  228):    at android.view.View.measure(View.java:7964)

E/AndroidRuntime(  228):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3023)

E/AndroidRuntime(  228):    at android.widget.FrameLayout.onMeasure(FrameLayout.java:245)

E/AndroidRuntime(  228):    at android.view.View.measure(View.java:7964)

E/AndroidRuntime(  228):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3023)

E/AndroidRuntime(  228):    at android.widget.FrameLayout.onMeasure(FrameLayout.java:245)

E/AndroidRuntime(  228):    at android.view.View.measure(View.java:7964)

E/AndroidRuntime(  228):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3023)

E/AndroidRuntime(  228):    at android.widget.FrameLayout.onMeasure(FrameLayout.java:245)

E/AndroidRuntime(  228):    at android.view.View.measure(View.java:7964)

E/AndroidRuntime(  228):    at android.view.ViewRoot.performTraversals(ViewRoot.java:763)

E/AndroidRuntime(  228):    at android.view.ViewRoot.handleMessage(ViewRoot.java:1633)

E/AndroidRuntime(  228):    at android.os.Handler.dispatchMessage(Handler.java:99)

E/AndroidRuntime(  228):    at android.os.Looper.loop(Looper.java:123)

E/AndroidRuntime(  228):    at android.app.ActivityThread.main(ActivityThread.java:4363)

E/AndroidRuntime(  228):    at java.lang.reflect.Method.invokeNative(Native Method)

E/AndroidRuntime(  228):    at java.lang.reflect.Method.invoke(Method.java:521)

E/AndroidRuntime(  228):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)

E/AndroidRuntime(  228):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)

E/AndroidRuntime(  228):    at dalvik.system.NativeStart.main(Native Method)

我的getView方法：

My getView method:

@Override
    public View getView(int position, View convertView, ViewGroup parent) {

        View view=convertView;
        ViewHolder holder;

        if(convertView==null){
            view=inflater.inflate(R.layout.list_item, null); 
            holder=new ViewHolder();
            holder.imgItemImage=(ImageView)view.findViewById(R.id.imgItemImage);
            holder.tvItemTitle=(TextView)view.findViewById(R.id.tvItemTitle);
            holder.tvItemDetails=(TextView)view.findViewById(R.id.tvItemDetails);
            view.setTag(holder);
        }else
            holder=(ViewHolder)view.getTag();

        holder.tvItemTitle.setText(data.get(position).getYear()+" "+data.get(position).getTitle());

        StringBuilder sb=new StringBuilder();
        sb.append(data.get(position).getPrice());
        sb.append("\n");
        sb.append(data.get(position).getCity());
        holder.tvItemDetails.setText(sb.toString());


        String imageUrl="http://myuri/"+data.get(position).getUrlList().get(0)+"/p-t.jpeg";
        holder.imgItemImage.setTag(imageUrl);

        imageLoader.displayImage(imageUrl, activity, holder.imgItemImage);

        return view;    
    }

在getView首次调用， convertView = NULL ，所以 ViewHolder 创建对象。但调用后 findViewById（...） ViewHolder类的所有成员仍在空。因此，这里有来历 NullPointerException异常。查看膨胀是successul，我可以调试过程中看到，查看对象包含 RelativeLayout的与它的孩子。
最糟糕的是，我并没有改变应用程序的这一部分之前就开始崩溃了！
这是推动我疯了！

When getView is first called, convertView=null, so ViewHolder object is created. But after calling findViewById(...) all members of ViewHolder class are still null. So, here are the origins NullPointerException. View inflating is successul as I can see during debug, view object contains RelativeLayout with it's children. The worst thing is that I haven't changed this part of app before it started crashing! This is driving me nuts!

推荐答案

你试过从头开始重新构建应用程序？
项目 - >清除

Have you tried to rebuild the application from scratch? Project -> Clean

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