我试图从去年谷歌IO的一个ViewHolder中采用Romain Guy的推荐列表来优化列表视图来自:http://www.softwarepassion.com/android-series-custom-listview-items-and-adapters/(感谢管理员),但每当我试图翻阅列表或甚至让它移动一点位,应用程序崩溃了,发生了什么?任何帮助将不胜感激:)这是我做的>
private class OrderAdapter extends ArrayAdapter<Order> {
private ArrayList<Order> items;
LayoutInflater mInflater;
public OrderAdapter(Context context, int textViewResourceId, ArrayList<Order> items) {
super(context, textViewResourceId, items);
mInflater = LayoutInflater.from(context);
this.items = items;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if (convertView == null) {
convertView = mInflater.inflate(R.layout.row, parent, false);
holder = new ViewHolder();
holder.tt = (TextView) convertView.findViewById(R.id.toptext);
holder.bt = (TextView) convertView.findViewById(R.id.bottomtext);
} else {
holder = (ViewHolder) convertView.getTag();
}
Order o = items.get(position);
if (o != null) {
if (holder.tt != null) {
holder.tt.setText("Name: " + o.getOrderName());
}
if (holder.bt != null) {
holder.bt.setText("Status: " + o.getOrderStatus());
}
}
return convertView;
}
}
这是我收到的错误消息,抱歉我不知道如何格式化>
致命异常:在android.widget.ListView的android.widget.AbsListView.obtainView(AbsListView.java:1294)的com.softberries.lve.SoftwarePassionView $ OrderAdapter.getView(SoftwarePassionView.java:98)中的主要java.lang.NullPointerException . 在Android.widget.AbsList.trackMotionScroll(AbsListView.java)的android.widget.ListView.fillGap(ListView.java:623)的android.widget.ListView.fillDown(ListView.java:652)中的makeAndAddView(ListView.java:1727) :2944)android.widget.AbsListView.onTouchEvent(AbsListView.java:2065)at android.widget.ListView.onTouchEvent(ListView.java:3315)at android.view.View.dispatchTouchEvent(View.java:3766)at android位于android.view.ViewGroup的android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:936)的android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:936)的.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:897) . dispatchTouchEvent(ViewGroup.java:936)位于com.android.internal.policy.impl.Phone的android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:936)窗口$ DecorView.superDispatchTouchEvent(PhoneWindow.java:1671)位于com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1107)的android.app.Activity.dispatchTouchEvent(Activity.java:2086)at com .android.internal.policy.impl.PhoneWindow $ DecorView.dispatchTouchEvent(PhoneWindow.java:1655)at android.view.ViewRoot.handleMessage(ViewRoot.java:1785)at android.os.Handler.dispatchMessage(Handler.java:99 )在java.lang的java.lang.reflect.Method.invokeNative(Native Method)的android.app.Looper.loop(Looper.java:123)上的android.app.ActivityThread.main(ActivityThread.java:4627) . 在com.android.internal.os.ZygoteInit.main的com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run(ZygoteInit.java:868)中反映了.Method.invoke(Method.java:521)(ZygoteInit.java: 626)at dalvik.system.NativeStart.main(Native Method)
2 回答
我看到
holder = (ViewHolder) convertView.getTag();
. 但我没有看到你在if (convertView == null) {...}
体内为convertView
调用setTag()
的位置 .所以,我想你忘了这句话:
很可能你得到的是ArrayIndexOutOfBound Exception . 使用数组适配器的 getCount() 方法来声明列表的大小 .