Java基础之Comparable与Comparator概述

Java基础之Comparable与Comparator概述

自然排序Comparable

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() {

}

publihttp://c 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(ObjeckIfXpHOrBt 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

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

@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));

}

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

@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));

}

版权声明：本文内容由网络用户投稿，版权归原作者所有，本站不拥有其著作权，亦不承担相应法律责任。如果您发现本站中有涉嫌抄袭或描述失实的内容，请联系我们jiasou666@gmail.com 处理，核实后本网站将在24小时内删除侵权内容。