有一个question的list，question中有questionId和一个pointIdList,pointIdList中都是字符串格式的pointId，请使用java代码将listzhuanc已pointId为key值，已questionid的集合为value的map

好的，下面是Java代码实现：

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class Main {
    public static void main(String[] args) {
        List<Question> questionList = new ArrayList<>();

        // 添加数据
        List<String> pointIdList1 = new ArrayList<>();
        pointIdList1.add("pointId1");
        pointIdList1.add("pointId2");
        Question question1 = new Question("questionId1", pointIdList1);
        questionList.add(question1);

        List<String> pointIdList2 = new ArrayList<>();
        pointIdList2.add("pointId3");
        pointIdList2.add("pointId4");
        Question question2 = new Question("questionId2", pointIdList2);
        questionList.add(question2);

        // 转换为Map
        Map<String, List<String>> map = new HashMap<>();
        for (Question question : questionList) {
            map.put(question.getQuestionId(), question.getPointIdList());
        }

        System.out.println(map); // 输出结果：{questionId1=[pointId1, pointId2], questionId2=[pointId3, pointId4]}
    }
}

class Question {
    private String questionId;
    private List<String> pointIdList;

    public Question(String questionId, List<String> pointIdList) {
        this.questionId = questionId;
        this.pointIdList = pointIdList;
    }

    public String getQuestionId() {
        return questionId;
    }

    public void setQuestionId(String questionId) {
        this.questionId = questionId;
    }

    public List<String> getPointIdList() {
        return pointIdList;
    }

    public void setPointIdList(List<String> pointIdList) {
        this.pointIdList = pointIdList;
    }
}

首先定义了一个Question类，包含了questionId和pointIdList两个属性。然后定义了一个questionList列表，包含了若干个Question对象。最后通过for循环，将questionList转换为一个Map对象，其中key值为questionId，value为pointIdList。最终输出了转换后的Map对象。