两种方法具有相同的擦除，但是都不能覆盖另一种方法

Question

'save(S)' in repositories clashes with 'save(S)' in 'org.springframework.data.repository.CrudRepository' both methods have same erasure, yet neither overrides the other.

I got this error. I'm trying to create an interface which is named as BookRepository. The interface extends CrudRepository and I want to implement save method and saveAll method inside that interface. When I implement all methods, all methods work fine except save() and saveAll().

I gave you my classes below.

BookRepository:

package repositories;

import com.ex.deneme_1.*;
import org.springframework.data.repository.CrudRepository;

import java.util.Optional;

public interface BookRepository extends CrudRepository<Book, Long>{

    @Override
    default  <S extends T> S save(S entity) { // That doesn't work
        return null;
    }

    @Override
    default <S extends T> Iterable<S> saveAll(Iterable<S> entities) { 
        //That doesn't work either
        return null;
    }

    @Override
    default Optional<Book> findById(Long id) {
        return null;
    }

    @Override
    default boolean existsById(Long id) {
        return false;
    }

    @Override
    default Iterable<Book> findAll() {
        return null;
    }

    @Override
    default Iterable<Book> findAllById(Iterable<Long> ids) {
        return null;
    }

    @Override
    default long count() {
        return 0;
    }

    @Override
    default void deleteById(Long id) {

    }

    @Override
    default void delete(Book entity) {

    }

    @Override
    default void deleteAll(Iterable<? extends Book> entities) {

    }

    @Override
    default void deleteAll() {

    }
}

My bootstrap class:

package Bootstrap;

import com.ex.deneme_1.*;
import org.springframework.context.ApplicationListener;
import org.springframework.context.event.ContextRefreshedEvent;
import org.springframework.stereotype.*;
import repositories.*;

@Component
public class DevBootstrap implements ApplicationListener<ContextRefreshedEvent>{

private BookRepository bookRepository;
private AuthorRepository authorRepository;

public DevBootstrap(AuthorRepository authorRepository, BookRepository bookRepository)
{
    this.authorRepository = authorRepository;
    this.bookRepository = bookRepository;
}

@Override
public void onApplicationEvent(ContextRefreshedEvent contextRefreshedEvent) {
    initData();
}


private void initData(){
    Author xyz = new Author("xyz","xyz");
    Book abc = new Book("Trying to learn Spring","1234","StackOverFlow");

    xyz.getBooks().add(abc);
    abc.getAuthors().add(xyz);

    authorRepository.save(xyz);
    bookRepository.save(abc);


}


}

And My Book Class:

    package com.ex.deneme_1;
    import javax.annotation.Generated;
    import javax.persistence.*;
    import java.util.HashSet;
    import java.util.Set;
    import java.awt.*;


@Entity



public class Book extends java.awt.print.Book {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private String title,isbn,publisher;
private long id;
@ManyToMany


 @JoinTable(name = "author_book", joinColumns = @JoinColumn(name="book_id"),
    inverseJoinColumns = @JoinColumn(name = "author_id"))

    private Set<Author> authors = new HashSet<>();

public Book(){

}

public Book(String title,String isbn, String publisher)
{
    this.title = title;
    this.isbn = isbn;
    this.publisher = publisher;
}

public Book(String title, String isbn, String publisher, Set<Author> author)
{
    this.title = title;
    this.isbn = isbn;
    this.publisher = publisher;
    this.authors = author;
}

public String getTitle() { return title; }
public String getIsbn() { return isbn; }
public String getPublisher() { return publisher; }
public Set<Author> getAuthors(){ return authors; }
public long getId() {
    return id;
}



public void setId(long id) {
    this.id = id;
}
public void setTitle(String title) { this.title = title; }
public void setIsbn(String isbn) { this.isbn = isbn; }
public void setPublisher(String publisher){ this.publisher = publisher; }
public void setAuthors(Set<Author> authors){ this.authors = authors; }


}

I think you guys easily guessed I have a class named as Author which has similar functions like Book.class.

Answer 1

由于您正在扩展CrudRepository，因此save方法将使用Book，这意味着save（Book实体）

Answer 2

Is there a particular reason you want to override the save method in CrudRepository? The way Spring data works is that it will automagically implement any interface extensions of the CrudRepository interface and provide you with out the box methods for saving entities so you shouldn't really need to override it.