Spring ClassCastException？

Question

java.lang.ClassCastException: class java.lang.Double 无法转换为 class java.lang.Integer （java.lang.Double 和 java.lang.Integer 在模块中java.base 加载程序 'bootstrap')

//using lombok
@Data
@AllArgsConstructor
@NoArgsConstructor
@Entity
public class Quiz {
    @Id
    @Column
    int id;

    @Column
    String title;

    @Column
    String text;

    @ElementCollection
    @Column
    List<String> options;

    @ElementCollection
    @Column
    List<Integer> answer = new ArrayList<>(); //this is obviously a list of Integers
}

@Service
public class QuizService {
    @Autowired
    Repo repo;

    public List<Quiz> getAllQuiz(){
        List<Quiz> quizList = new ArrayList<>();
        repo.findAll().forEach(quiz -> quizList.add(quiz));
        return quizList;
    }

    public void saveNewQuiz(Quiz quiz){
        repo.save(quiz); //error occurred here
    }

    public void deleteQuiz(Quiz quiz){
        repo.delete(quiz);
    }
}

import engine.Quiz;
import org.springframework.data.repository.CrudRepository;

public interface Repo extends CrudRepository<Quiz, Integer> {
}

    @PostMapping(value = "/api/quizzes", produces = "application/json")
    @ResponseBody
    public String newQuiz(@RequestBody String json){
        Import();
        Gson gson = new Gson();
        JsonObject jObj = new JsonObject();
        try {
            jObj = new JsonParser().parse(json).getAsJsonObject();
        }catch(Exception e){
            throw new ResponseStatusException(HttpStatus.BAD_REQUEST);
        }
        //test out the json
        requestHandler(jObj);

        Quiz quiz = new Quiz();
        int id = idGenerator();
        quiz.setId(id);
        quiz.setTitle(jObj.get("title").getAsString());
        quiz.setText(jObj.get("text").getAsString());
        quiz.setOptions(gson.fromJson(jObj.get("options").getAsJsonArray(), List.class));
        try {
            List<Integer> list = gson.fromJson(jObj.get("answer").getAsJsonArray(), List.class);
            quiz.setAnswer(list);
        }catch(Exception ignored) {}
        quizzes.add(quiz);
        service.saveNewQuiz(quiz); //error occured here

        return getQuiz(id);
    }

我什至从未接触过 Double，怎么会有从 Double 到 Integer 的 class 转换异常？

我不能做的事情：

我无法将类型从 Integer 更改为 Double，因为项目需要整数才能运行。
我无法更改数据库，因为该项目需要 h2 数据库

这个异常让我很困惑。

Answer 1

我就是这样解决这个问题的；首先，我没有从 json 获取列表，而是尝试获取一个 int[]，使用它并转换为列表

Spring ClassCastException？

Spring ClassCastException?

java

spring

h2