Android Gridview/CursorAdapter nullPointerException
我似乎不知道这个代码出了什么问题。我收到的最后一条Log.d消息是“我们在getView中”。之后出现了一个错误,如下所示。我是否正确使用了getView、newView和bindView 错误:Android Gridview/CursorAdapter nullPointerException,android,gridview,android-cursoradapter,Android,Gridview,Android Cursoradapter,我似乎不知道这个代码出了什么问题。我收到的最后一条Log.d消息是“我们在getView中”。之后出现了一个错误,如下所示。我是否正确使用了getView、newView和bindView 错误: 02-28 15:22:54.063: E/AndroidRuntime(10855): FATAL EXCEPTION: main 02-28 15:22:54.063: E/AndroidRuntime(10855): Process: com.example.wwwww_testi, PID:
02-28 15:22:54.063: E/AndroidRuntime(10855): FATAL EXCEPTION: main
02-28 15:22:54.063: E/AndroidRuntime(10855): Process: com.example.wwwww_testi, PID: 10855
02-28 15:22:54.063: E/AndroidRuntime(10855): java.lang.NullPointerException
02-28 15:22:54.063: E/AndroidRuntime(10855): at android.widget.AbsListView.obtainView(AbsListView.java:2265)
02-28 15:22:54.063: E/AndroidRuntime(10855): at android.widget.GridView.onMeasure(GridView.java:1044)
02-28 15:22:54.063: E/AndroidRuntime(10855): at android.view.View.measure(View.java:16497)
02-28 15:22:54.063: E/AndroidRuntime(10855): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
02-28 15:22:54.063: E/AndroidRuntime(10855): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
02-28 15:22:54.063: E/AndroidRuntime(10855): at android.view.View.measure(View.java:16497)
02-28 15:22:54.063: E/AndroidRuntime(10855): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
02-28 15:22:54.063: E/AndroidRuntime(10855): at com.android.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:327)
02-28 15:22:54.063: E/AndroidRuntime(10855): at android.view.View.measure(View.java:16497)
02-28 15:22:54.063: E/AndroidRuntime(10855): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
02-28 15:22:54.063: E/AndroidRuntime(10855): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
02-28 15:22:54.063: E/AndroidRuntime(10855): at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2291)
02-28 15:22:54.063: E/AndroidRuntime(10855): at android.view.View.measure(View.java:16497)
02-28 15:22:54.063: E/AndroidRuntime(10855): at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1916)
02-28 15:22:54.063: E/AndroidRuntime(10855): at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1113)
02-28 15:22:54.063: E/AndroidRuntime(10855): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1295)
02-28 15:22:54.063: E/AndroidRuntime(10855): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1000)
02-28 15:22:54.063: E/AndroidRuntime(10855): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5670)
02-28 15:22:54.063: E/AndroidRuntime(10855): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761)
02-28 15:22:54.063: E/AndroidRuntime(10855): at android.view.Choreographer.doCallbacks(Choreographer.java:574)
02-28 15:22:54.063: E/AndroidRuntime(10855): at android.view.Choreographer.doFrame(Choreographer.java:544)
02-28 15:22:54.063: E/AndroidRuntime(10855): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747)
02-28 15:22:54.063: E/AndroidRuntime(10855): at android.os.Handler.handleCallback(Handler.java:733)
02-28 15:22:54.063: E/AndroidRuntime(10855): at android.os.Handler.dispatchMessage(Handler.java:95)
02-28 15:22:54.063: E/AndroidRuntime(10855): at android.os.Looper.loop(Looper.java:136)
02-28 15:22:54.063: E/AndroidRuntime(10855): at android.app.ActivityThread.main(ActivityThread.java:5017)
02-28 15:22:54.063: E/AndroidRuntime(10855): at java.lang.reflect.Method.invokeNative(Native Method)
02-28 15:22:54.063: E/AndroidRuntime(10855): at java.lang.reflect.Method.invoke(Method.java:515)
02-28 15:22:54.063: E/AndroidRuntime(10855): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
02-28 15:22:54.063: E/AndroidRuntime(10855): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
02-28 15:22:54.063: E/AndroidRuntime(10855): at dalvik.system.NativeStart.main(Native Method)
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<GridView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/gridView1"
android:numColumns="auto_fit"
android:gravity="center"
android:columnWidth="50dp"
android:stretchMode="columnWidth"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
</GridView>
编辑:这为我解决了问题:
@Override
public View getView(int position, View convertView, ViewGroup parent) {
Log.d(LOG_TAG, "We're in getView");
View v;
if (convertView == null) {
v = newView(mContext, cursor, parent);
} else {
v = convertView;
}
bindView(v, mContext, cursor);
return v;
}
getView
不能返回null,否则Android无法测量绘制元素所需的空间量。可以避免重写该方法 getView
不能返回null,否则Android无法测量绘制元素所需的空间量。可以避免重写该方法 getView
不能返回null,否则Android无法测量绘制元素所需的空间量。可以避免重写该方法 getView
不能返回null,否则Android无法测量绘制元素所需的空间量。可以避免重写该方法 您有返回null代码>在getView
中,当它需要查看时感谢您的快速帮助!您有返回null代码>在getView
中,当它需要查看时感谢您的快速帮助!您有返回null代码>在getView
中,当它需要查看时感谢您的快速帮助!您有返回null代码>在getView
中,当它需要查看时感谢您的快速帮助!谢谢你的回答,我会调查这件事并在我确认它解决了问题后立即接受。谢谢你的回答,我会调查这件事并在我确认它解决了问题后立即接受。谢谢你的回答,我会调查这件事并在我确认它解决了问题后立即接受。谢谢你的回答,我将对此进行调查,并在验证它解决了问题后尽快接受它。
public class GridAdapter extends CursorAdapter {
private Context mContext;
private LayoutInflater mInflater;
private final String LOG_TAG = "GridAdapter";
private ViewHolder holder;
public GridAdapter(Context context, Cursor c, boolean autoRequery) {
super(context, c, autoRequery);
this.mContext = context;
mInflater = LayoutInflater.from(context);
Log.d(LOG_TAG, "We're in constructor");
}
public static class ViewHolder {
public TextView txtView;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
Log.d(LOG_TAG, "We're in getView");
return null;
}
@Override
public void bindView(View view, Context context, Cursor cursor) {
Log.d(LOG_TAG, "We're in bindView");
holder = (ViewHolder) view.getTag();
int headerIndex = cursor.getColumnIndex(ArticleTable.MAIN_HEADER);
String header = cursor.getString(headerIndex);
holder.txtView.setText(header);
}
@Override
public View newView(Context context, Cursor cursor, ViewGroup parent) {
Log.d(LOG_TAG, "We're in newView");
View view = mInflater.inflate(R.layout.grid_item, parent, false);
holder = new ViewHolder();
holder.txtView = (TextView) view.findViewById(R.id.header);
view.setTag(holder);
return view;
}
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
Log.d(LOG_TAG, "We're in getView");
View v;
if (convertView == null) {
v = newView(mContext, cursor, parent);
} else {
v = convertView;
}
bindView(v, mContext, cursor);
return v;
}