java list 根据对象一个字段去重

最新推荐文章于 2025-06-21 15:59:00 发布

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本文介绍了一种通过重写equals和hashCode方法实现Java对象去重的方法。以PullThroughAnalysisUser类为例，展示了如何根据value1属性进行对象去重的具体实现。

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1.主要思路就是根据从写equals 以及 hashCode 方法。

代码如下：

package com.bfd.unibase.modules.dataview.entity;

import org.hibernate.validator.constraints.Length;

import java.util.ArrayList;
import java.util.Date;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;

import com.fasterxml.jackson.annotation.JsonFormat;

import javax.validation.constraints.NotNull;

import com.bfd.unibase.common.persistence.DataEntity;

/**
* test
* @author kui.peng
* @version 2015-10-22
*/
public class PullThroughAnalysisUser extends DataEntity<PullThroughAnalysisUser> {

   private static final long serialVersionUID = 1L;

   private String value1;       //
   private String value2;       //


   public String getValue1() {
       return value1;
   }
   public void setValue1(String value1) {
       this.value1 = value1;
   }
   public String getValue2() {
       return value2;
   }
   public void setValue2(String value2) {
       this.value2 = value2;
   }
   @Override
   public boolean equals(Object obj) {
       PullThroughAnalysisUser s=(PullThroughAnalysisUser)obj;
       return value1.equals(s.value1);

// 根据value1 属性去重    }
   @Override
   public int hashCode() {
       String in = value1;
       return in.hashCode();
   }

   public static void main(String[] args) {
       List< PullThroughAnalysisUser> listTest = new ArrayList<PullThroughAnalysisUser>();

       PullThroughAnalysisUser pullThroughAnalysisUser = new PullThroughAnalysisUser();
       pullThroughAnalysisUser.setValue1("wwww&mmmm");

       pullThroughAnalysisUser.setValue2("2222");

       PullThroughAnalysisUser pullThroughAnalysisUser2 = new PullThroughAnalysisUser();
       pullThroughAnalysisUser2.setValue1("wwww&mmmm");
       pullThroughAnalysisUser2.setValue2("3333");

       PullThroughAnalysisUser pullThroughAnalysisUser3 = new PullThroughAnalysisUser();
       pullThroughAnalysisUser3.setValue1("mmm");
       pullThroughAnalysisUser3.setValue2("3333");
       listTest.add(pullThroughAnalysisUser3);
       listTest.add(pullThroughAnalysisUser2);
       listTest.add(pullThroughAnalysisUser);



       Set<PullThroughAnalysisUser> set = new HashSet<PullThroughAnalysisUser>();
       set.addAll(listTest);
       Iterator<PullThroughAnalysisUser> it = set.iterator();

       /*while(it.hasNext()){

           System.out.println("00000000");
           System.out.println(it.next().getValue1());
           System.out.println(it.next().getValue2());
       }*/
       for (PullThroughAnalysisUser student : set) {
                System.out.println(student.getValue1()+"-"+student.getValue2());
            }

   }



}

输入结果：