无法加载图像列表视图

Question

我试图添加图像ListView到我的应用程序，但其显示错误。

这是我的logcat

02-28 09:57:11.263: E/AndroidRuntime(10348): FATAL EXCEPTION: main 
02-28 09:57:11.263: E/AndroidRuntime(10348): java.lang.NullPointerException 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.widget.AbsListView.obtainView(AbsListView.java:2467) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.widget.ListView.measureHeightOfChildren(ListView.java:1250) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.widget.ListView.onMeasure(ListView.java:1162) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.view.View.measure(View.java:15371) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.widget.RelativeLayout.measureChild(RelativeLayout.java:602) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:415) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.view.View.measure(View.java:15371) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4876) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.view.View.measure(View.java:15371) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.widget.LinearLayout.measureVertical(LinearLayout.java:833) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.widget.LinearLayout.onMeasure(LinearLayout.java:574) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.view.View.measure(View.java:15371) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4876) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2423) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.view.View.measure(View.java:15371) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2011) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1250) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1425) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1143) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4674) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:725) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.view.Choreographer.doCallbacks(Choreographer.java:555) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.view.Choreographer.doFrame(Choreographer.java:525) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:711) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.os.Handler.handleCallback(Handler.java:615) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.os.Handler.dispatchMessage(Handler.java:92) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.os.Looper.loop(Looper.java:137) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at android.app.ActivityThread.main(ActivityThread.java:4960) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at java.lang.reflect.Method.invokeNative(Native Method) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at java.lang.reflect.Method.invoke(Method.java:511) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1038) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:805) 
02-28 09:57:11.263: E/AndroidRuntime(10348): at dalvik.system.NativeStart.main(Native Method) 

这是活动代码

int images[] = {R.drawable.a, R.drawable.b, R.drawable.c, R.drawable.d}; 
list = (ListView) findViewById(R.id.listView1); 
ItemsAdapter adapter = new ItemsAdapter(getApplicationContext(), images); 
list.setAdapter(adapter); 

这是适配器类代码。

public class ItemsAdapter extends ArrayAdapter<Integer> { 

    private final Context context; 
    private final int[] values; 

    ItemsAdapter(Context context, int[] values) { 
     super(context, R.layout.items_list_item); 
     this.context = context; 
     this.values = values; 
} 

    @Override 
    public int getCount() { 
     // TODO Auto-generated method stub 
     return values.length; 
    } 

    @Override 
    public Integer getItem(int arg0) { 
     // TODO Auto-generated method stub 
     return arg0; 
    } 

    @Override 
    public long getItemId(int position) { 
     // TODO Auto-generated method stub 
     return position; 
    } 

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

     LayoutInflater inflater = (LayoutInflater) context 
     .getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
     View rowView = inflater.inflate(R.layout.items_list_item, parent, false); 
     ImageView imageView = (ImageView) rowView.findViewById(R.id.list_item_image); 
     imageView.setImageResource(values[position]); 

     return convertView; 

    } 
} 

任何人都可以帮助我解决这个错误。

Answer 1

这是做它的正确方法：

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

     LayoutInflater inflater = (LayoutInflater) context 
     .getSystemService(Context.LAYOUT_INFLATER_SERVICE); 

     View rowView = convertView; 

     if (null == convertView) 
      rowView = inflater.inflate(R.layout.items_list_item, parent, false); 

     ImageView imageView = (ImageView) rowView.findViewById(R.id.list_item_image); 
     imageView.setImageResource(values[position]); 
     return rowView ; 

    } 

Answer 2

您应该返回rowView

return rowView; 

而不是convertView

return convertView; 

进入你的ItemsAdapter