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;
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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