模板模式和Comparable类

模板模式中，父类规定好了一些算法的流程，并且空出一些步骤（方法）留给子类填充

Java的数组类中静态方法sort()就是一个模板，它空出了一个compareTo的方法，留给子类填充，用来规定什么是大于、等于和小于

 

package com.example.template;



public class Duck implements Comparable<Duck>{



    private String name;

    private int weight;

    

    public Duck(String name, int weight){

        this.name = name;

        this.weight = weight;

    }

    

    public String toString(){

        return "name" + name + "weight" + weight;

    }

    

    @Override

    public int compareTo(Duck other) {



        if(this.weight < other.weight){

            return -1;

        }else if(this.weight > other.weight){

            return 1;

        }        

        return 0;

    }

}

package com.example.template;



import java.util.Random;



public class Employee implements Comparable<Employee> {



    private String name;

    private int id;

    private double salary;

    

    public Employee(String name, double salary){

        this.name = name;

        this.salary = salary;

        Random ra = new Random();

        this.id = ra.nextInt(1000000);

    }

    

    public String toString(){

        return "name:" + name + " salary:" + salary + " ElyId:" + id;

    }

    

    @Override

    public int compareTo(Employee other) {

        if(this.id < other.id){

            return -1;

        }else if(this.id > other.id){

            return 1;

        }

        return 0;

    }



}

package com.example.template;



import java.util.Arrays;



public class Test {



    public static void main(String[] args)

    {

        Duck[] ducks = new Duck[4];



        ducks[0] = new Duck("Jason", 89);

        ducks[1] = new Duck("Amemle", 100);

        ducks[2] = new Duck("Mike", 72);

        ducks[3] = new Duck("Ham", 102);

        

        System.out.println("before sort:");

        for(int i = 0 ; i < ducks.length ; i++)

            System.out.println(ducks[i].toString());

        

        Arrays.sort(ducks);

        

        System.out.println("after sort:");

        for(int i = 0 ; i < ducks.length ; i++)

            System.out.println(ducks[i].toString());

        

        Employee[] emps = {

            new Employee("Jason", 999.0),

            new Employee("Canson", 1599.1),

            new Employee("Jack", 887.9)

        };

        

        System.out.println("--------------------");

        

        System.out.println("before sort:");

        for(int i = 0 ; i < emps.length ; i++)

            System.out.println(emps[i].toString());

        

        Arrays.sort(emps);

        

        System.out.println("after sort:");

        for(int i = 0 ; i < emps.length ; i++)

            System.out.println(emps[i].toString());

        

    }

}

结果：

before sort:
nameJasonweight89
nameAmemleweight100
nameMikeweight72
nameHamweight102
after sort:
nameMikeweight72
nameJasonweight89
nameAmemleweight100
nameHamweight102
--------------------
before sort:
name:Jason salary:999.0 ElyId:502862
name:Canson salary:1599.1 ElyId:716871
name:Jack salary:887.9 ElyId:552929
after sort:
name:Jason salary:999.0 ElyId:502862
name:Jack salary:887.9 ElyId:552929
name:Canson salary:1599.1 ElyId:716871