Java基础之Comparable与Comparator概述

对于自定义类进行排序要实现Comparable接口，重写compareTo() 方法,如果不重写，像使用Arrays.sort()排序就会报错

package com.che.lambda;import java.util.Objects;/** * @author cheyuhang on 2021/4/23 */public class Good implements Comparable{ private String name; private Double price; public Good(String name, Double price) {this.name = name;this.price = price; } public Good() { } public String getName() {return name; } public void setName(String name) {this.name = name; } public Double getPrice() {return price; } public void setPrice(Double price) {this.price = price; } @Override public boolean equals(Object o) {if (this == o) return true;if (o == null || getClass() != o.getClass()) return false;Good good = (Good) o;return Objects.equals(name, good.name) && Objects.equals(price, good.price); } @Override public int hashCode() {return Objects.hash(name, price); } @Override public String toString() {return 'Good{' +'name=’' + name + ’’’ +', price=' + price +’}’; } @Override public int compareTo(Object o) {if (o instanceof Good){ //判断传递参数是否属于商品 Good good=(Good) o; if(this.price >good.price){return 1; }else if(this.price <good.price) {return -1; }else {return 0; }}throw new RuntimeException('传入数据类型不一致'); }}定制排序Comparator

使用场景：当类没有实现Comparable接口或者实现了Comparable接口，但不符合我期望的排序规则时进行使用

@Test public void test02() {Good[] arr=new Good[5];arr[0] =new Good('zhangsan',234.0);arr[1] =new Good('lisi',2343.0);arr[2] =new Good('wangwu',2354.0);arr[3] =new Good('zhaoliu',2334.0);arr[4] =new Good('tianqi',2347.0);System.out.println(Arrays.toString(arr));Arrays.sort(arr, new Comparator<Object>() @Override public int compare(Object o1, Object o2) {if (o1 instanceof Good && o2 instanceof Good){ Good g1=(Good) o1; Good g2=(Good) o2; return Double.compare(g1.getPrice(),g2.getPrice()); //return g1.compareTo(g2);}throw new RuntimeException('数据类型不一致'); }});System.out.println(Arrays.toString(arr)); }

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