策略模式小练习

编程技术  /  houtizong 发布于 3年前   141

练习：
假如有若干个person对象保存在list对象之中，对它们分别用id，姓名，年龄进行排序（正序/倒序），如果年龄或者姓名重复，则按照id的升序进行排序。要求使用策略模式进行。
Person对象

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;}}

1、抽象策略类

public interface Strategy {public void sort(List<Person> list);}

2、具体实现类(按id倒序排，其它略)

public class IdDescStrategy implements Strategy, Comparator<Person> {@Overridepublic void sort(List<Person> list) {Collections.sort(list, this);}@Overridepublic int compare(Person p1, Person p2) {return p2.getId() - p1.getId();}}

3、环境类

public class Environment {private Strategy strategy ;public Environment(Strategy strategy) {this.strategy = strategy;}public void setStrategy(Strategy strategy) {this.strategy = strategy;}public void sort(List<Person> list) { this.strategy.sort(list);}}

4、客户端

public static void main(String[] args) {IdDescStrategy iddesc = new IdDescStrategy();Environment environment = new Environment(iddesc);List<Person> list = new ArrayList<Person>();Person p1 = new Person(1, "wangxiaoxiao", 10);Person p2 = new Person(2, "zhangshan", 20);Person p3 = new Person(3, "lisi", 30);Person p4 = new Person(4, "wangwu", 40);Person p5 = new Person(5, "wangke", 50);list.add(p1);list.add(p2);list.add(p3);list.add(p4);list.add(p5);environment.sort(list);for(Person p : list){System.out.println(p.getId()+", "+p.getName()+", "+p.getAge());}}