我在我的ExpandableListView中的getChildView
上获得了NullPointerException,但不确定原因。组列表显示很好,但是当我点击一个组来显示孩子时,我得到了NullPointerException。谁能告诉我我失踪了什么?
public class LazyAdapter extends BaseExpandableListAdapter {
private Activity activity;
private ArrayList<HashMap<String, String>> groups;
private ArrayList<HashMap<String, String>> child;
private static LayoutInflater inflater = null;
public ImageLoader imageLoader;
private DatabaseHandler dbh;
int flag;
static class RowHolder {
TextView name;
TextView id;
TextView reference;
TextView vicinity;
TextView lastcheck;
TextView number_checkins;
TextView user;
ImageView user_image;
ImageView checkin;
}
public LazyAdapter(Activity a, ArrayList<HashMap<String, String>> d,
ArrayList<HashMap<String, String>> e) {
activity = a;
groups = d;
child = e;
inflater = (LayoutInflater)
activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
imageLoader = new ImageLoader(activity.getApplicationContext());
dbh = new DatabaseHandler(activity);
}
public void clearData() {
// clear the data
groups.clear();
}
public Object getChild(int groupPosition, int childPosition) {
return ((HashMap<String, String>)child.get(groupPosition)).get(childPosition);
}
public long getChildId(int groupPosition, int childPosition) {
return childPosition;
}
public int getChildrenCount(int groupPosition) {
return ((HashMap<String, String>)child.get(groupPosition)).size();
}
public View getChildView(int groupPosition, int childPosition, boolean isLastChild,View
convertView, ViewGroup parent) {
View vi = convertView;
RowHolder holder = null;
if(convertView == null) {
vi = inflater.inflate(R.layout.child_view, null);
holder = new RowHolder();
holder.user_image = (ImageView) convertView.findViewById(R.id.user_image);
holder.user = (TextView) convertView.findViewById(R.id.user);
vi.setTag(holder);
} else {
holder = (RowHolder) vi.getTag();
}
HashMap<String, String> userList;
userList = child.get(groupPosition);
imageLoader.DisplayImage(userList.get(MainActivity.KEY_USERIMAGE),
holder.user_image);
holder.user.setText(userList.get(MainActivity.KEY_USER));
return convertView;
}
public Object getGroup(int groupPosition) {
return groups.get(groupPosition);
}
public int getGroupCount() {
return groups.size();
}
public long getGroupId(int groupPosition) {
return groupPosition;
}
public View getGroupView(int groupPosition, boolean isExpanded, View
convertView,ViewGroup parent) {
View vi = convertView;
RowHolder holder = null;
if (convertView == null) {
vi = inflater.inflate(R.layout.group_view, null);
holder = new RowHolder();
holder.number_checkins = (TextView) vi.findViewById(R.id.number_checkins);
holder.id = (TextView) vi.findViewById(R.id.id);
holder.name = (TextView) vi.findViewById(R.id.name);
holder.vicinity = (TextView) vi.findViewById(R.id.vicinity);
holder.lastcheck = (TextView) vi.findViewById(R.id.lastcheck);
holder.checkin = (ImageView) vi.findViewById(R.id.check_in);
vi.setTag(holder);
} else {
holder = (RowHolder) vi.getTag();
}
HashMap<String, String> placeList;
placeList = groups.get(groupPosition);
holder.id.setText(placeList.get(MainActivity.KEY_ID));
holder.name.setText(placeList.get(MainActivity.KEY_NAME));
holder.vicinity.setText(placeList.get(MainActivity.KEY_VICINITY));
holder.lastcheck.setText(placeList.get(MainActivity.KEY_LASTCHECK));
holder.number_checkins.setText(placeList.get(MainActivity.KEY_NUMBERCHECKINS));
return vi;
}
public boolean isChildSelectable(int groupPosition, int childPosition) {
return true;
}
public boolean hasStableIds() {
return true;
}
}
日志:
FATAL EXCEPTION: main java.lang.NullPointerException at
lazylist.LazyAdapter.getChildView(LazyAdapter.java:85)
at android.widget.ExpandableListConnector.getView(ExpandableListConnector.java:450)
at android.widget.AbsListView.obtainView(AbsListView.java:2046)
at android.widget.ListView.measureHeightOfChildren(ListView.java:1292)
at android.widget.ListView.onMeasure(ListView.java:1155)
at android.view.View.measure(View.java:13011)
at android.widget.RelativeLayout.measureChild(RelativeLayout.java:579)
at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:392)
at android.view.View.measure(View.java:13011)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4706)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:293)
at android.view.View.measure(View.java:13011)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:812)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:553)
at android.view.View.measure(View.java:13011)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4706)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:293)
at
com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2162)
at android.view.View.measure(View.java:13011)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1091)
at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2505)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:4945)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分:2)
问题是您检查convertView == null
,但初始化vi
,然后继续使用convertView
。
我会放弃vi
并初始化convertView
。
注意:强> 如果您认为这样做:
vi = convertView;
vi = something;
convertView现在alao引用something
,那么你的理解是错误的,应该查看java引用。