Comparable

最新推荐文章于 2025-07-31 12:17:16 发布

原创最新推荐文章于 2025-07-31 12:17:16 发布 · 106 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#对象比较 #Comparable

java 专栏收录该内容

33 篇文章

订阅专栏

本文通过两个示例展示了如何使用Java的集合框架进行数据去重。第一个示例使用`LinkedList`结合`Collections.sort()`方法对`Person`对象列表进行排序并去重；第二个示例则利用`TreeSet`的特性直接实现对`Person`对象的去重。这两个示例不仅演示了不同集合类的特点，还深入介绍了如何实现`Comparable`接口来定制对象比较逻辑。


package org.lxh.demo13.setdemo;

import java.util.LinkedList;
import java.util.List;
import java.util.Collections;

class Person implements Comparable<Person>{

	private String name;
	private int age;

	public Person(String name, int age) {
		this.name = name;
		this.age = age;
	}

	public boolean equals(Object obj) {
		if(this == obj) {
			return true;
		}

		if(!(obj instanceof Person)) {
			return false;
		}

		Person p = (Person)obj;

		if(this.name.equals(p.name)&&this.age == p.age) {
			return true;
		}else {
			return false;
		}		
	}

	public int hashCode() {
		return this.name.hashCode() * this.age;
	}

	public String toString() {
		return "姓名：" + this.name + ";年龄：" + this.age;
	}

	public int compareTo(Person per) {	
		if(this.age > per.age) {
			return 1;
		}else if(this.age < per.age) {
			return -1;
		}else {
			return this.name.compareTo(per.name);
		}
	}	
}

public class RepeatDemo02 {

	/**
	 * @param args
	 */
	public static void main(String[] args) {	
		List<Person> allList = new LinkedList<Person>();
		allList.add(new Person("李四",31)) ;
		allList.add(new Person("王五",32)) ;
		allList.add(new Person("王五",32)) ;
		allList.add(new Person("王五",32)) ;
		allList.add(new Person("赵六",33)) ;
		allList.add(new Person("孙七",33)) ;
		allList.add(new Person("张三",30)) ;
		System.out.println(allList);	//没排序
		Collections.sort(allList);   //必须调用一下sort，否则没有任何效果
		System.out.println(allList); //排序了
	}
}


package com.mldn.compare.sort;

import java.util.Set;
import java.util.TreeSet;

class Person implements Comparable<Person>{

	private String name;
	private int age;

	public Person(String name, int age) {
		this.name = name;
		this.age = age;
	}

	public boolean equals(Object obj) {
		if(this == obj) {
			return true;
		}

		if(!(obj instanceof Person)) {
			return false;
		}

		Person p = (Person)obj;

		if(this.name.equals(p.name)&&this.age == p.age) {
			return true;
		}else {
			return false;
		}		
	}

	public int hashCode() {
		return this.name.hashCode() * this.age;
	}

	public String toString() {
		return "姓名：" + this.name + ";年龄：" + this.age;
	}

	public int compareTo(Person per) {	
		if(this.age > per.age) {
			return 1;
		}else if(this.age < per.age) {
			return -1;
		}else {
			return this.name.compareTo(per.name);
		}
	}

}

public class RepeatDemo03 {

	/**
	 * @param args
	 */
	public static void main(String[] args) {

		Set<Person> allSet = new TreeSet<Person>() ;
		allSet.add(new Person("李四",31)) ;
		allSet.add(new Person("王五",32)) ;
		allSet.add(new Person("王五",32)) ;
		allSet.add(new Person("王五",32)) ;
		allSet.add(new Person("赵六",33)) ;
		allSet.add(new Person("孙七",33)) ;
		allSet.add(new Person("张三",30)) ;
		System.out.println(allSet); //排序了

	}

}