Spring Boot java：找不到符号

Question

我是新学员 有人可以帮助我吗..我遵循了本教程，但仍然收到错误。 我按照每个步骤给出了相同的文件名，变量仍然相同。我犯了什么错误无法克服

https://www.youtube.com/watch?v=YgkTXsqWvno&t=550s&ab_channel=JavaExpress

package com.example.demo.dto;

//import com.example.demo.model.Address;
//import com.example.demo.model.Credential;
//import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonProperty;
import jakarta.persistence.*;
import lombok.*;

import java.io.Serializable;
import java.util.Set;

@NoArgsConstructor
@AllArgsConstructor
@Builder
@Setter
@Getter

public class UserDto implements Serializable {


    private static final long serialVersionUID = 1L;

    private Integer userId;
    private String firstName;
    private String lastName;
    private String email;
    private String phone;

    private Set<AddressDto> addressDtos;

    @JsonProperty("credential")
    @JsonInclude(value = JsonInclude.Include.NON_NULL)
    private CredentialDatato credentialDto;

}

package com.example.demo.helper;

import com.example.demo.dto.UserDto;
import com.example.demo.model.Credential;
import com.example.demo.model.User;
import org.springframework.beans.BeanUtils;
//import com.example.demo.model.User;

public interface UserMappingHelper {

    public static UserDto map(User user) {
        return null;
    }

    public static User map(UserDto userDto) {
            if(userDto == null)
            {
                return null;
            }
            User user = new User();
            BeanUtils.copyProperties(userDto,user);

            if(userDto.getCredentialDto() != null)
            {
                Credential credential = new Credential();
                BeanUtils.copyProperties(userDto.getCredentialDto(),credential);

                credential.setUser(user);
                user.setCredential(credential);
            }
            return user;


    }

}

这是输出。

C:\Users\User\Downloads\Spring_microservice\demo\src\main\java\com\example\demo\helper\UserMappingHelper.java:23:23
java: cannot find symbol
  symbol:   method getCredentialDto()
  location: variable userDto of type com.example.demo.dto.UserDto

Answer 1

“Java：找不到符号”错误是编译错误。经过研究，我发现正是这一行导致了错误： public static UserDto map(User user) { 返回空值； }。这可能是因为你如何定义它。即使在其他语言中，这样做也可能会出现问题。如果问题仍然存在，请评论，我会再试一次。 干杯。