[해결 방법] java.lang.IllegalArgumentException

👉 기본 환경

- Language: Java

- DB: H2 Database

- IDE: IntelliJ

 

 

⌨️ 코드

public class Main {
    public static void main(String[] args) {
 
        EntityManagerFactory emf = Persistence.createEntityManagerFactory("hello");
 
        EntityManager em = emf.createEntityManager();
 
        EntityTransaction tx = em.getTransaction();
        tx.begin(); // transaction 시작 선언
 
        try {
            Member member1 = new Member();
            member1.setName("Member1");
            em.persist(member1);
 
            Member member2 = new Member();
            member2.setName("Member1");
            em.persist(member2);
 
            // Scala Type Projection
            em.createQuery("select distinct m.name, m.age from Member m", Order.class)
                    .getResultList();
 
            tx.commit(); // transaction 종료 후 commit
        } catch (Exception e) {
            tx.rollback(); // 문제가 생길 경우, rollback 진행
            e.printStackTrace();
        } finally {
            em.close(); // tx에 문제가 생기더라도 em 반드시 종료
        }
 
        emf.close();
 
    }
}
 

 

 

🖨️오류

java.lang.IllegalArgumentException: Cannot create TypedQuery for query with more than one return using requested result type [jpql.Order]
    at org.hibernate.internal.AbstractSharedSessionContract.resultClassChecking(AbstractSharedSessionContract.java:870)
    at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:817)
    at org.hibernate.internal.AbstractSessionImpl.createQuery(AbstractSessionImpl.java:23)
    at jpql.Main.main(Main.java:54)
 

 

 

📡 원인

return type이 불일치

 

 

📰 해결 방법

public class Main {
    public static void main(String[] args) {
 
        EntityManagerFactory emf = Persistence.createEntityManagerFactory("hello");
 
        EntityManager em = emf.createEntityManager();
 
        EntityTransaction tx = em.getTransaction();
        tx.begin(); // transaction 시작 선언
 
        try {
            Member member1 = new Member();
            member1.setName("Member1");
            em.persist(member1);
 
            Member member2 = new Member();
            member2.setName("Member1");
            em.persist(member2);
 
            // Scala Type Projection
            em.createQuery("select distinct m.name, m.age from Member m")
                    .getResultList();
 
            tx.commit(); // transaction 종료 후 commit
        } catch (Exception e) {
            tx.rollback(); // 문제가 생길 경우, rollback 진행
            e.printStackTrace();
        } finally {
            em.close(); // tx에 문제가 생기더라도 em 반드시 종료
        }
 
        emf.close();
 
    }
}
 

return 타입 생략