lombok @EqualsAndHashCode 注解如何让对象.equals()方法只比较部分属性

墨蓝 2023-09-28 12:01 20阅读 0赞

实体类

import lombok.Data;
    import lombok.EqualsAndHashCode;
    
    
    @Data
    @EqualsAndHashCode
    public class Cs {
        
        private int id;
        private String name;
    
        public Cs(int id, String name) {
        
            this.id = id;
            this.name = name;
        }
    }

运行

public static void main(String[] args) {
        
            Cs cs1=new Cs(1,"小小");
            Cs cs2=new Cs(1,"小小");
            System.out.println(cs1.equals(cs2));
        }

查看生成的class文件

//
    // Source code recreated from a .class file by IntelliJ IDEA
    // (powered by Fernflower decompiler)
    //
    
    package com.hieasy.rftools.common;
    
    public class Cs {
        
        private int id;
        private String name;
    
        public Cs(int id, String name) {
        
            this.id = id;
            this.name = name;
        }
    
        public int getId() {
        
            return this.id;
        }
    
        public String getName() {
        
            return this.name;
        }
    
        public void setId(int id) {
        
            this.id = id;
        }
    
        public void setName(String name) {
        
            this.name = name;
        }
    
        public String toString() {
        
            return "Cs(id=" + this.getId() + ", name=" + this.getName() + ")";
        }
    
        public boolean equals(Object o) {
        
            if (o == this) {
        
                return true;
            } else if (!(o instanceof Cs)) {
        
                return false;
            } else {
        
                Cs other = (Cs)o;
                if (!other.canEqual(this)) {
        
                    return false;
                } else if (this.getId() != other.getId()) {
        
                    return false;
                } else {
        
                    Object this$name = this.getName();
                    Object other$name = other.getName();
                    if (this$name == null) {
        
                        if (other$name != null) {
        
                            return false;
                        }
                    } else if (!this$name.equals(other$name)) {
        
                        return false;
                    }
    
                    return true;
                }
            }
        }
    
        protected boolean canEqual(Object other) {
        
            return other instanceof Cs;
        }
    
        public int hashCode() {
        
            int PRIME = true;
            int result = 1;
            int result = result * 59 + this.getId();
            Object $name = this.getName();
            result = result * 59 + ($name == null ? 43 : $name.hashCode());
            return result;
        }
    }

如果我们去掉注解是一样的，全部比较的话可以不要@EqualsAndHashCode注解

//
    // Source code recreated from a .class file by IntelliJ IDEA
    // (powered by Fernflower decompiler)
    //
    
    package com.hieasy.rftools.common;
    
    public class Cs {
        
        private int id;
        private String name;
    
        public Cs(int id, String name) {
        
            this.id = id;
            this.name = name;
        }
    
        public int getId() {
        
            return this.id;
        }
    
        public String getName() {
        
            return this.name;
        }
    
        public void setId(int id) {
        
            this.id = id;
        }
    
        public void setName(String name) {
        
            this.name = name;
        }
    
        public boolean equals(Object o) {
        
            if (o == this) {
        
                return true;
            } else if (!(o instanceof Cs)) {
        
                return false;
            } else {
        
                Cs other = (Cs)o;
                if (!other.canEqual(this)) {
        
                    return false;
                } else if (this.getId() != other.getId()) {
        
                    return false;
                } else {
        
                    Object this$name = this.getName();
                    Object other$name = other.getName();
                    if (this$name == null) {
        
                        if (other$name != null) {
        
                            return false;
                        }
                    } else if (!this$name.equals(other$name)) {
        
                        return false;
                    }
    
                    return true;
                }
            }
        }
    
        protected boolean canEqual(Object other) {
        
            return other instanceof Cs;
        }
    
        public int hashCode() {
        
            int PRIME = true;
            int result = 1;
            int result = result * 59 + this.getId();
            Object $name = this.getName();
            result = result * 59 + ($name == null ? 43 : $name.hashCode());
            return result;
        }
    
        public String toString() {
        
            return "Cs(id=" + this.getId() + ", name=" + this.getName() + ")";
        }
    }

但是我们如果只想比较name属性的话，类上需要加入@EqualsAndHashCode(onlyExplicitlyIncluded = true)，想只比较哪些属性就在属性上加@EqualsAndHashCode.Include

import lombok.Data;
    import lombok.EqualsAndHashCode;
    
    /**
     * @author Zc
     * @date 2022年06月24日 16:04
     */
    @Data
    @EqualsAndHashCode(onlyExplicitlyIncluded = true)
    public class Cs {
        
        private int id;
        @EqualsAndHashCode.Include
        private String name;
    
        public Cs(int id, String name) {
        
            this.id = id;
            this.name = name;
        }
    }

结果  
![在这里插入图片描述][21b731e94b04410fa2d5fa493e4cf305.png]

[21b731e94b04410fa2d5fa493e4cf305.png]: https://img-blog.csdnimg.cn/21b731e94b04410fa2d5fa493e4cf305.png