我实现了一个自定义列表视图，包含4个不同的自定义行。当我在一个屏幕上显示所有行时，每件事都有效。但是，当我将屏幕切换为横向格式，然后列表视图必须滚动。 当我向下滚动并且顶部的第一个项目消失时，应用程序崩溃了！
以下是getView方法中的代码：
View row = null;
if(convertView==null){
LayoutInflater inflater = LayoutInflater.from(context);
switch (rowFinder[position]){
case 1:
row = inflater.inflate(R.layout.header_sidebar_row, parent, false);
break;
case 2:
row = inflater.inflate(R.layout.current_club, parent, false);
break;
case 3:
row = inflater.inflate(R.layout.custom_sidebar_row, parent, false);
break;
case 4:
row = inflater.inflate(R.layout.section_sidebar_header, parent, false);
break;
}
}
else{
row = convertView;
}
TextView sidebarTitle;
ImageView iconImage = null;
switch (rowFinder[position]){
case 1:
sidebarTitle =(TextView) row.findViewById(R.id.user_name);
iconImage = (ImageView) row.findViewById(R.id.user_image);
break;
case 2:
sidebarTitle =(TextView) row.findViewById(R.id.club_name);
iconImage = (ImageView) row.findViewById(R.id.club_image);
break;
case 3:
sidebarTitle =(TextView) row.findViewById(R.id.menu_item);
iconImage = (ImageView) row.findViewById(R.id.icon_image);
break;
case 4:
sidebarTitle =(TextView) row.findViewById(R.id.section_item);
iconImage = null;
break;
default:
sidebarTitle = (TextView) row.findViewById(R.id.menu_item);
iconImage = null;
break;
}
sidebarTitle.setText(titlesSideMenu[position]);
if(iconImage != null){
iconImage.setImageResource(images[position]);
}
return row;
}
（并非所有自定义行都有图像）
这是崩溃报告：
10-05 20:02:08.710: E/InputEventReceiver(2126): Exception dispatching input event.
10-05 20:02:08.730: D/AndroidRuntime(2126): Shutting down VM
10-05 20:02:08.743: W/dalvikvm(2126): threadid=1: thread exiting with uncaught exception (group=0x40a71930)
10-05 20:02:08.800: E/AndroidRuntime(2126): FATAL EXCEPTION: main
10-05 20:02:08.800: E/AndroidRuntime(2126): java.lang.NullPointerException
10-05 20:02:08.800: E/AndroidRuntime(2126): at com.example.rivler.SidebarListAdapter.getView(SidebarListAdapter.java:125)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.widget.AbsListView.obtainView(AbsListView.java:2143)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.widget.ListView.makeAndAddView(ListView.java:1831)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.widget.ListView.fillDown(ListView.java:674)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.widget.ListView.fillGap(ListView.java:638)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.widget.AbsListView.trackMotionScroll(AbsListView.java:4930)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.widget.AbsListView.scrollIfNeeded(AbsListView.java:3087)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.widget.AbsListView.onTouchEvent(AbsListView.java:3361)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.view.View.dispatchTouchEvent(View.java:7246)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2168)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1903)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
10-05 20:02:08.800: E/AndroidRuntime(2126): at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1953)
10-05 20:02:08.800: E/AndroidRuntime(2126): at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1405)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.app.Activity.dispatchTouchEvent(Activity.java:2410)
10-05 20:02:08.800: E/AndroidRuntime(2126): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1901)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.view.View.dispatchPointerEvent(View.java:7426)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.view.ViewRootImpl.deliverPointerEvent(ViewRootImpl.java:3220)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:3165)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:4292)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:4271)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:4363)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:179)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.view.InputEventReceiver.nativeConsumeBatchedInputEvents(Native Method)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.view.InputEventReceiver.consumeBatchedInputEvents(InputEventReceiver.java:171)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.view.ViewRootImpl.doConsumeBatchedInput(ViewRootImpl.java:4342)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.view.ViewRootImpl$ConsumeBatchedInputRunnable.run(ViewRootImpl.java:4382)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.view.Choreographer.doCallbacks(Choreographer.java:562)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.view.Choreographer.doFrame(Choreographer.java:530)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.os.Handler.handleCallback(Handler.java:725)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.os.Handler.dispatchMessage(Handler.java:92)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.os.Looper.loop(Looper.java:137)
10-05 20:02:08.800: E/AndroidRuntime(2126): at android.app.ActivityThread.main(ActivityThread.java:5041)
10-05 20:02:08.800: E/AndroidRuntime(2126): at java.lang.reflect.Method.invokeNative(Native Method)
10-05 20:02:08.800: E/AndroidRuntime(2126): at java.lang.reflect.Method.invoke(Method.java:511)
10-05 20:02:08.800: E/AndroidRuntime(2126): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
10-05 20:02:08.800: E/AndroidRuntime(2126): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
10-05 20:02:08.800: E/AndroidRuntime(2126): at dalvik.system.NativeStart.main(Native Method)
求助，我将非常感激！
答案 0 :(得分：0)
切换屏幕位置时，将再次生成视图。如果你尝试使用一些旧视图的引用，它将不再存在，导致你到达那里的NullPointerException。
检查this another answer以获取有关如何处理屏幕旋转的进一步说明。
答案 1 :(得分：0)
如果要在适配器中使用多个布局，有两个重要方法需要覆盖：
getViewTypeCount：必须返回适配器使用的不同布局的数量
getItemViewType：必须返回介于0和getViewTypeCount之间的int - 1
在您的情况下，您需要添加
@Override
public int getViewTypeCount() {
return 4;
}
@Override
public int getItemViewType(int position) {
return rowFinder[position] - 1;
}
通过实现这些方法，convertView将始终具有正确的类型，您将无法找到您的观点。
注意：要提高效果，请将ViewHolder添加为视图标记