从Firebase

Question

Process: com.example.berkbatuhangurhan.pollmanagerapp, PID: 313
              com.google.firebase.database.DatabaseException: Class java.util.List has generic type parameters, please use GenericTypeIndicator instead

我已经搜索了有关我的问题的其他问题，但他们似乎没有工作。我试图从Firebase中检索我的Poll对象并继续收到上面的消息; 我尝试过使用Lists，HashMaps，Generic类型的paramateres，但我没有运气。我在这里虽然有点欢迎任何帮助

DatabaseReference ref =  FirebaseDatabase.getInstance().getReference("polls");

    ref.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            Poll p1=null;
            for(DataSnapshot childSnapShot:dataSnapshot.getChildren()) {
                p1=childSnapShot.getValue(Poll.class);
            }
            Poll post =dataSnapshot.getValue(Poll.class);

            Toast.makeText(main_activity.this, "A= "+p1.getPollCreator(), Toast.LENGTH_SHORT).show();
        }

您可以在下面找到我的民意调查课程：

public class Poll  {
public String pollTitle;
public String pollCreatorEmail;
public Date dateCreated;
public List<Question> questions;
public Date deadLine;
public List<Integer> votes;
public int pollPrivacy;
public boolean pendStatus=false;

public Poll(String pollTitle, String pollCreatorEmail, int pollPrivacy,boolean pendStatus){
    this.pollTitle=pollTitle;
    this.pollCreatorEmail=pollCreatorEmail;
    //this.dateCreated=dateCreated;
    //this.questions=questions;
    //this.deadLine=deadLine;
    //this.votes=votes;
    this.pollPrivacy=pollPrivacy;
    this.pendStatus=pendStatus;
    questions=new ArrayList<Question>();
    votes=new ArrayList<Integer>();
}
public Poll(){}

public String getPollTitle(){
    return pollTitle;
}
public void setPollTitle(String newTitle){
    pollTitle=newTitle;
}
public String getPollCreator(){
    return pollCreatorEmail;
}
public void setPollCreator(String pollCreatorEmail){
    this.pollCreatorEmail=pollCreatorEmail;
}
// SKIPPED ATTRIBUTE METHODS
public List<Question> getQuestions(){
    return questions;
}
public void setQuestions(List<Question> questions){
        this.questions=questions;
}
public Date getDeadLine(){
    return deadLine;
}
public void setDeadLine(Date newDeadLine){
    deadLine=newDeadLine;
}
public void sharePoll(){

}
public void addQuestion(Question question){
    questions.add(question);
}
public void deleteQuestion(Question question){
    questions.remove(question);
}
public List<Integer> getVotes(){
    return votes;
}
public void setVotes(Integer index){
    votes.add(index,votes.get(index)+1);
}
public void votePoll(Question question){
    //????????????????????????????
}
public void setPollPrivacy(int privacy){
    pollPrivacy=privacy;
}
public int getPollPrivacy(){
    return pollPrivacy;
}
}

我的数据库结构

-Polls   -PollTitle1      -pollCreator      -状态      -Questions           -1              -qText              -qNum   -PollTitle2