Comparable 比拟器,内置定义的比拟办法,实现比拟 较简略
Comparator 策略模式,须要定义不同的策略和比拟的对象,实现比拟 较简单
打个比方,狗有 foot 一种属性咱们用 Comparable 比拟器实现比拟
猫有 height 和 weight 两种属性,咱们用 Comparator 策略模式实现比拟
一、Comparable – 狗比拟
毛病:自定义排序规定,规定定义好之后,再改起来就不不便,还须要从新开发 Sort 比拟类
1、狗对象
package com.longze.guosh.strategy;
public class Dog implements Comparable<Dog> {
int food; // 狗的饭量
public Dog(int food){this.food=food;}
@Override // 自定义排序规定,规定定义好之后,再改起来就不不便
public int compareTo(Dog d) {if(this.food<d.food) return -1;
else if(this.food>d.food) return 1;
else return 0;
}
@Override
public String toString() {
return "Dog{" +
"food=" + food +
'}';
}
}
2、狗的比拟类,也能够代表猫的汽车的比拟类,然而比拟策略无奈批改((除非改原来的办法))
package com.longze.guosh.strategy;
import java.util.Comparator;
public class DogSorter {
// 排序
public static void sort(Comparable[] arr){for(int i=0;i< arr.length-1;i++){
int minPos=i;
for(int j=i+1;j<arr.length;j++){minPos=arr[j].compareTo(arr[minPos])==-1?j:minPos;
}
swap(arr,i,minPos);
}
}
// 替换
static void swap(Comparable[] arr,int i,int j){Comparable temp=arr[i];
arr[i]=arr[j];
arr[j]=temp;
}
}
3、main 办法验证
package com.longze.guosh.strategy;
import java.util.Arrays;
public class Main {
public static void main(String[] args) {Dog[] ds= {new Dog(8),new Dog(5),new Dog(10),new Dog(1)};
//comparater
DogSorter dogsorter=new DogSorter();
dogsorter.sort(ds);
System.out.println("Dogs==="+Arrays.toString(ds));
}
}
二、Comparator 策略模式
长处,能够定义多种比拟策略,不须要改 sort 比拟类
1、猫对象
package com.longze.guosh.strategy;
public class Cat{
int weight,height;
public Cat(int weight,int height){
this.height=height;
this.weight=weight;
}
@Override
public String toString() {
return "Cat{" +
"weight=" + weight +
", height=" + height +
'}';
}
}
2、猫的比拟策略,能够有多种策略
如【CatHeightComparator.java】身高比拟器【CatWeightComparator】体重比拟器
package com.longze.guosh.strategy;
import java.util.Comparator;
public class CatHeightComparator implements Comparator<Cat> {
@Override
public int compare(Cat o1, Cat o2) {if (o1.height > o2.height) {return -1;} else if (o1.height < o2.height) {return 1;}else {return 0;}
}
}
package com.longze.guosh.strategy;
import java.util.Comparator;
public class CatWeightComparator implements Comparator<Cat> {
@Override
public int compare(Cat o1, Cat o2) {if (o1.weight < o2.weight) {return -1;} else if (o1.weight > o2.weight) {return 1;}else {return 0;}
}
}
3、比拟器 也能够用作狗或者其余比拟类,比拟策略能够从新指定不同的
package com.longze.guosh.strategy;
import java.util.Comparator;
public class Sorter<T> {public void sort(T[] arr, Comparator<T> comparator){for(int i=0;i< arr.length-1;i++){
int minPos=i;
for(int j=i+1;j<arr.length;j++){minPos=comparator.compare(arr[j],arr[minPos])==-1?j:minPos;
}
swap(arr,i,minPos);
}
}
void swap(T[] arr,int i,int j){T temp=arr[i];
arr[i]=arr[j];
arr[j]=temp;
}
}
4、Main 校验
package com.longze.guosh.strategy;
import java.util.Arrays;
public class Main {public static void main(String[] args) {Cat[] cs={new Cat(3,3),new Cat(5,5),new Cat(1,1),new Cat(10,10)};
//comparator
Sorter<Cat> catsorter=new Sorter<>();
catsorter.sort(cs,new CatHeightComparator());
System.out.println("Cat==="+Arrays.toString(cs));
}
}
综上所述 应用简略比拟器间接实现 Comparable 类,就能够实现
当应用策略模式时,须要实现不同的 Comparator 策略,配合 Sort 能够实现比拟