Question

我尝试将图片ListView添加到我的应用程序中。但它显示错误。

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;

    }
}

任何人都可以帮我修复此错误。

Answer 1

您应该返回rowView

 return rowView;

而不是convertView

return convertView;

进入ItemsAdapter

Answer 2

这是正确的做法：

@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 ;

    }

无法加载图片列表视图

2 个答案: