java8 Stream 一行代码实现列表去重

通常情况下，实现列表去重的方式有：

1. 创建一个新的result列表，循环原列表，如果元素不在result列表中，则放入
2. 创建一个HashSet，将列表作为构造参数传入

下面介绍一种简单、高效的去重方式，借助于java8新特性引入的Stream类。代码如下

package cn.zokoo.goods.entity.dto;

import java.io.Serializable;
import java.util.Date;
import java.util.List;
import java.util.Objects;

import com.fasterxml.jackson.annotation.JsonInclude;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;


/**
 * 商品分类
 * 
 * @author Jack chen
 * @email [e-mail]
 * @date 2018-12-10 17:14:36
 */
@Data
@NoArgsConstructor
@AllArgsConstructor
@JsonInclude(JsonInclude.Include.NON_NULL)
public class MchCatDTO implements Serializable {
	private static final long serialVersionUID = 1L;
	
	/**
	 * 分类编号
	 */
    private Integer catId;
	
	/**
	 * 分类编码
	 */
    private String catCode;
	
	/**
	 * 分类名称
	 */
    private String catName;
	
	/**
	 * 上级分类编码
	 */
    private String parentCatCode;
	
	/**
	 * 排序
	 */
    private Integer sortOrder;
    
    
    // 商户号
    private String mchNo;
    
    //新增类型  1-导入   2-普通品类   3-活动品类
    private String catType;
	
	/**
	 * 分类图标
	 */
    private String catIcon;
	
	/**
	 * 是否显示：0-否 1-是
	 */
    private String isShow;
	
	/**
	 * 备注
	 */
    private String remark;
	
	/**
	 * 版本号
	 */
    private Integer version;
	
	/**
	 * 创建时间
	 */
    private Date createTime;
	
	/**
	 * 创建操作员
	 */
    private String createOprNo;
	
	/**
	 * 修改时间
	 */
    private Date modifiedTime;
	
	/**
	 * 修改操作员
	 */
    private String editOprNo;
    
    private List<MchCatDTO> childList;
    
    private Long count;

    public MchCatDTO(String catCode, String parentCatCode) {
        this.catCode = catCode;
        this.parentCatCode = parentCatCode;
    }
    
    public MchCatDTO(String catCode, String parentCatCode,String catName) {
        this.catCode = catCode;
        this.parentCatCode = parentCatCode;
        this.catName = catName;
    }

    public MchCatDTO(Integer catId, String catCode, String catName, Integer sortOrder, String catIcon) {
        this.catId = catId;
        this.catCode = catCode;
        this.catName = catName;
        this.sortOrder = sortOrder;
        this.catIcon = catIcon;
    }
    
    
    public MchCatDTO(String catCode,String catName,String parentCatCode,Long count,String catType,Date createTime) {
        this.catCode = catCode;
        this.parentCatCode = parentCatCode;
        this.catName = catName;
        this.count = count;
        this.catType = catType;
        this.createTime = createTime;
    }
    
	
    @Override
    public boolean equals(Object o) {
      if (this == o) return true;
      if (o == null || getClass() != o.getClass()) return false;
      MchCatDTO cat = (MchCatDTO) o;
      return Objects.equals(this.catCode, cat.catCode) &&
        Objects.equals(this.catName, cat.catName);
    }
   
    @Override
    public int hashCode() {
   
      return Objects.hash(this.catCode,this.catName);

    }
}

 

 

去重解决：catList = catList.stream().distinct().collect(Collectors.toList());