[Java知识库]List转成Set去重案例代码

package com.tuling.kafka.kafkaDemo.Command;

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

/**
 * @USER: hx
 * @DATE: 2022/4/27
 **/
public class SetTest {


    private String name;


    private String age;
    private String aa;


    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAge() {
        return age;
    }

    public void setAge(String age) {
        this.age = age;
    }

    public String getAa() {
        return aa;
    }

    public void setAa(String aa) {
        this.aa = aa;
    }


    public static void main(String[] args) {
        SetTest setTest1 = new SetTest();
        setTest1.setAa("aa");
        setTest1.setAge("aaAge");
        setTest1.setName("aaName");

        SetTest setTest2 = new SetTest();
        setTest2.setAa("aa");
        setTest2.setAge("aaAge");
        setTest2.setName("aaName");

        SetTest setTest3 = new SetTest();
        setTest3.setAa("aa");
        setTest3.setAge("aaAge");
        setTest3.setName("aaName");

        SetTest setTest4 = null;



        List<SetTest> setTestList = new ArrayList<SetTest>();
        setTestList.add(setTest4);
        setTestList.add(setTest1);
        setTestList.add(setTest2);
        setTestList.add(setTest4);
        setTestList.add(setTest3);
        setTestList.add(setTest4);

        Set<SetTest> setTestSet = new HashSet<SetTest>();
        setTestSet.addAll(setTestList);
//        setTestSet.add(setTest1);
//        setTestSet.add(setTest2);
//        setTestSet.add(setTest3);

        System.out.println("setTestSet.size:  " + setTestSet.size());
        System.out.println("setTestList.size:  " + setTestList.size());


        for (SetTest setTest : setTestList) {
            if (setTest == null){
                continue;
            }
            System.out.println("setTestList输出：" + setTest.getAa() + ":" + setTest.getAge() + ":" + setTest.getName());
        }


        System.out.println("-----------------------------------------------------------------");
        System.out.println("-----------------------------------------------------------------");
        System.out.println("-----------------------------------------------------------------");


        for (SetTest setTest : setTestSet) {

            if (setTest == null){
                continue;
            }

            System.out.println("setTestSet输出：" + setTest.getAa() + ":" + setTest.getAge() + ":" + setTest.getName());
        }


        Set<String> set = new HashSet<String>();
        set.add("1");
        set.add("1");
        set.add("1");
        for (String setTest : set) {
            System.out.println("测试set是否有重复数据：" + setTest);
        }
    }

    /**
     * 2，在比较equals的属性值，实现去重
     * @param obj
     * @return
     */
    @Override
    public boolean equals(Object obj) {
        if (obj == null) {
            return true;
        }
        SetTest setTest = (SetTest) obj;
        if (String.valueOf(this.getName()).equals(String.valueOf(setTest.getName()))) {
            return true;
        }
        return false;
    }

    /**
     * 1.先重写hashcode方法，让其一样
     * @return
     */
    @Override
    public int hashCode() {
        return 1;
    }

//    public int compareTo(SetTest o) {
//        if (String.valueOf(this.getName()).equals(String.valueOf(o.getName()))) {
//            return 0;
//        }
//        else {
//            return -1;
//        }
//    }
}

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