我哪里错了？首先使用适配器等创建了一个测试可扩展列表视图。但是当我尝试连接时，它给出了一个错误。
Attempt to invoke interface method 'java.lang.Object java.util.List.get(int)' on a null object reference
esport.inyourlife.insport.ExpListAdapter.getChildView
这是这里，我正在尝试通过数据模型显示列表
package esport.inyourlife.insport.Consts;
public class Tournaments {
public String id;
public String TournName;
public String TAdress;
public String ToDate;
public String ToTime;
public String creator;
public String sport;
public String format;
public String pole;
public String level;
public String minyear;
public String maxteams;
public String info;
public Tournaments() {
}
public Tournaments(String id, String TName, String TAdress, String TDate, String TTime,
String creator, String format, String level, String minyear, String maxteams,
String info, String pole, String sport) {
this.id = id;
this.TournName = TName;
this.TAdress = TAdress;
this.ToDate = TDate;
this.ToTime = TTime;
this.creator = creator;
this.format = format;
this.level = level;
this.minyear = minyear;
this.maxteams = maxteams;
this.info = info;
this.pole = pole;
this.sport = sport;
}
}
这是适配器代码
package esport.inyourlife.insport;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseExpandableListAdapter;
import android.widget.TextView;
import java.util.ArrayList;
import java.util.List;
import esport.inyourlife.insport.Consts.Tournaments;
public class ExpListAdapter extends BaseExpandableListAdapter {
private ArrayList<List<Tournaments>> mGroups;
private Context mContext;
public ExpListAdapter (Context context, ArrayList<List<Tournaments>> groups){
mContext = context;
mGroups = groups;
}
@Override
public int getGroupCount() {
return mGroups.size();
}
@Override
public int getChildrenCount(int groupPosition) {
return mGroups.size();
}
@Override
public Object getGroup(int groupPosition) {
return mGroups.get(groupPosition);
}
@Override
public Object getChild(int groupPosition, int childPosition) {
return mGroups.get(groupPosition).get(childPosition);
}
@Override
public long getGroupId(int groupPosition) {
return groupPosition;
}
@Override
public long getChildId(int groupPosition, int childPosition) {
return childPosition;
}
@Override
public boolean hasStableIds() {
return true;
}
@Override
public View getGroupView(int groupPosition, boolean isExpanded, View convertView,
ViewGroup parent) {
if (convertView == null) {
LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = inflater.inflate(R.layout.group_view, null);
}
if (isExpanded){
//Изменяем что-нибудь, если текущая Group раскрыта
}
else{
//Изменяем что-нибудь, если текущая Group скрыта
}
TextView textGroup = (TextView) convertView.findViewById(R.id.textGroup);
if (groupPosition==0){
textGroup.setText("Football");
} else if (groupPosition==1){
textGroup.setText("Basketball");
}
return convertView;
}
@Override
public View getChildView(int groupPosition, int childPosition, boolean isLastChild,
View convertView, ViewGroup parent) {
if (convertView == null) {
LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = inflater.inflate(R.layout.child_view, null);
}
TextView textChild = (TextView) convertView.findViewById(R.id.textChild);
textChild.setText((mGroups.get(groupPosition).get(childPosition)).ToDate);
return convertView;
}
@Override
public boolean isChildSelectable(int groupPosition, int childPosition) {
return true;
}
}以及我在需要时应用它的代码
ArrayList<List<Tournaments>> groups = new ArrayList<>();
ArrayList<String> listDatas = new ArrayList<String>();
ArrayList<Tournaments> children2 = new ArrayList<>();
FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();
DatabaseReference reference = FirebaseDatabase.getInstance().getReference();
reference.child("Users").child(user.getUid()).child("Tournaments").addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot snapshot) {
if (listDatas.size() > 0) {
listDatas.clear();
}
for (DataSnapshot dataSnapshot : snapshot.getChildren()) {
Tournaments getTurn = dataSnapshot.getValue(Tournaments.class);
if (getTurn != null) {
listTemp.add(getTurn);
/*listDatas.add(getTurn.TournName + ", " + getTurn.sport + ", " + getTurn.format +
", " + getTurn.TAdress + ", " + getTurn.ToDate + "." + getTurn.ToTime +
", " + getTurn.minyear);*/
} } }@Override public void onCancelled(@NonNull DatabaseError error) {}
});
groups.add(listTemp);
groups.add(children2);
//Создаем адаптер и передаем context и список с данными
ExpListAdapter adapter = new ExpListAdapter(getActivity(), groups);
turnirs.setAdapter(adapter);