【小程序】用策略模式完成自定义类的排序（改进版）

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题目：假如有若干Person对象存放在一个List当中，对他们进行排序，分别按name,ID,age排序（要有正序和逆序），若名字或年龄一样按ID正序排列。

Person类

public class Person{   private int id;   private String name;   private int age;   public Person(int id,String name,int age){this.id= id;this.name= name;this.age= age;}public int getId(){return id;}public void setId(int id){this.id = id;}public String getName(){return name;}public void setName(String name){this.name = name;}public int getAge(){return age;}public void setAge(int age){this.age = age;}@Overridepublic int hashCode(){final int prime = 31;int result = 1;result = prime * result + age;result = prime * result + id;result = prime * result + ((name == null) ? 0 : name.hashCode());return result;}@Overridepublic boolean equals(Object obj){if (this == obj)return true;if (obj == null)return false;if (getClass() != obj.getClass())return false;Person other = (Person) obj;if (age != other.age)return false;if (id != other.id)return false;if (name == null){if (other.name != null)return false;}else if (!name.equals(other.name))return false;return true;}@Overridepublic String toString(){return "Person [id=" + id + ", name=" + name + ", age=" + age + "]";}   }

策略的公共接口

import java.util.List;public interface PersonSort{    public void sort(List<Person> list);   }

策略类

1.按ID升序排序

import java.util.Collections;import java.util.Comparator;import java.util.List;public class IdUpsort implements PersonSort,Comparator<Person>{@Overridepublic void sort(List<Person> list){Collections.sort(list,this);}public int compare(Person o1, Person o2) {return o1.getId()-o2.getId();}}

按ID降序排序

import java.util.Collections;import java.util.Comparator;import java.util.List;public class IdDnsort implements Comparator<Person>, PersonSort{@Overridepublic void sort(List<Person> list){Collections.sort(list,this);}public int compare(Person o1, Person o2) {return o2.getId()-o1.getId();}}

2.按年龄升序排序

import java.util.Collections;import java.util.Comparator;import java.util.List;public class AgeUpsort implements PersonSort,Comparator<Person>{@Overridepublic void sort(List<Person> list){Collections.sort(list,this);}@Overridepublic int compare(Person o1, Person o2){          int result = o1.getAge()-o2.getAge();          if(result==0)          {          return o1.getId()-o2.getId();          }            return result;}}

按年龄降序排序

import java.util.Collections;import java.util.Comparator;import java.util.List;public class AgeDnsort implements Comparator<Person>, PersonSort{@Overridepublic void sort(List<Person> list){           Collections.sort(list,this);}@Overridepublic int compare(Person o1,Person o2){   int result = o2.getAge()-o1.getAge();   if(result==0)   {   return o1.getId()-o2.getId();   }   return result;}}

3.按名字升序排序

import java.util.Collections;import java.util.Comparator;import java.util.List;public class NameUpsort implements PersonSort,Comparator<Person>{    @Override    public void sort(List<Person> list)    { Collections.sort(list,this);    }      @Override     public int compare(Person o1, Person o2)    {      int result = o1.getName().compareTo(o2.getName());      if(result==0)      {      return o1.getId()-o2.getId();      }      return result;    }}

按名字降序排序

import java.util.Collections;import java.util.Comparator;import java.util.List;public class NameDnsort implements PersonSort, Comparator<Person>{    @Override    public void sort(List<Person> list)    { Collections.sort(list,this);    }      @Override     public int compare(Person o1, Person o2)    {      int result = o2.getName().compareTo(o1.getName());      if(result==0)      {      return o1.getId()-o2.getId();      }      return result;    }}

封装策略类的环境类

import java.util.List;public class Environment{   private PersonSort personsort;    public Environment(PersonSort personsort)   {   this.personsort = personsort;   }   public PersonSort getPersonsort()   {    return personsort;   }   public void setPersonsort(PersonSort personsort)   {   this.personsort = personsort;   }   public void sort(List<Person> list)   {   personsort.sort(list);   }}

测试类

import java.util.ArrayList;import java.util.List;public class StrategyTest{public static void main(String[] args){         Person p1 = new Person(201001,"zhangsan",24);         Person p2 = new Person(201004,"lisi",19);         Person p3 = new Person(201003,"zhangsan",25);         Person p4 = new Person(201002,"zhaoliu",27);         Person p5 = new Person(201006,"lisi",24);         Person p6 = new Person(201005,"kuroro",24);         List<Person> list = new ArrayList<Person>();         list.add(p1);         list.add(p2);         list.add(p3);         list.add(p4);         list.add(p5);         list.add(p6);         System.out.println("排序前状态：");         System.out.println(list);         System.out.println("-----------------------");         Environment en = new Environment(new IdUpsort());         en.sort(list);         System.out.println("按ID正序排列：");         System.out.println(list);         en.setPersonsort(new IdDnsort());         en.sort(list);         System.out.println("按ID逆序排列：");         System.out.println(list);         System.out.println("-----------------------");         en.setPersonsort(new AgeUpsort());         en.sort(list);         System.out.println("按年龄正序排列：");         System.out.println(list);         en.setPersonsort(new AgeDnsort());         en.sort(list);         System.out.println("按年龄逆序排列：");         System.out.println(list);         System.out.println("-----------------------");         en.setPersonsort(new NameUpsort());         en.sort(list);         System.out.println("按名字正序排列：");         System.out.println(list);         en.setPersonsort(new NameDnsort());         en.sort(list);         System.out.println("按名字逆序排列：");         System.out.println(list);    }                                }

打印结果

排序前状态：
[Person [id=201001, name=zhangsan, age=24], Person [id=201004, name=lisi, age=19], Person [id=201003, name=zhangsan, age=25], Person [id=201002, name=zhaoliu, age=27], Person [id=201006, name=lisi, age=24], Person [id=201005, name=kuroro, age=24]]
-----------------------
按ID正序排列：
[Person [id=201001, name=zhangsan, age=24], Person [id=201002, name=zhaoliu, age=27], Person [id=201003, name=zhangsan, age=25], Person [id=201004, name=lisi, age=19], Person [id=201005, name=kuroro, age=24], Person [id=201006, name=lisi, age=24]]
按ID逆序排列：
[Person [id=201006, name=lisi, age=24], Person [id=201005, name=kuroro, age=24], Person [id=201004, name=lisi, age=19], Person [id=201003, name=zhangsan, age=25], Person [id=201002, name=zhaoliu, age=27], Person [id=201001, name=zhangsan, age=24]]
-----------------------
按年龄正序排列：
[Person [id=201004, name=lisi, age=19], Person [id=201001, name=zhangsan, age=24], Person [id=201005, name=kuroro, age=24], Person [id=201006, name=lisi, age=24], Person [id=201003, name=zhangsan, age=25], Person [id=201002, name=zhaoliu, age=27]]
按年龄逆序排列：
[Person [id=201002, name=zhaoliu, age=27], Person [id=201003, name=zhangsan, age=25], Person [id=201001, name=zhangsan, age=24], Person [id=201005, name=kuroro, age=24], Person [id=201006, name=lisi, age=24], Person [id=201004, name=lisi, age=19]]
-----------------------
按名字正序排列：
[Person [id=201005, name=kuroro, age=24], Person [id=201004, name=lisi, age=19], Person [id=201006, name=lisi, age=24], Person [id=201001, name=zhangsan, age=24], Person [id=201003, name=zhangsan, age=25], Person [id=201002, name=zhaoliu, age=27]]
按名字逆序排列：
[Person [id=201002, name=zhaoliu, age=27], Person [id=201001, name=zhangsan, age=24], Person [id=201003, name=zhangsan, age=25], Person [id=201004, name=lisi, age=19], Person [id=201006, name=lisi, age=24], Person [id=201005, name=kuroro, age=24]]