Java之策略模式比较器案例讲解

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  //自定义排序规则，规则定义好之后，再改起来就不方便
    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 +
                '}';
    }
}

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);
        }
    }
    //交换
    static void swap(Comparable[] arr,int i,int j){
        Comparable temp=arr[i];
        arr[i]=arr[j];
        arr[j]=temp;
    }
}

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));
 
    }
}

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 +
                '}';
    }
}

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;
        }
    }
}

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;
    }
 
}

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));
 
    }
}