정책 모드 연습

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;
	}
	
}

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

public class IdDescStrategy implements Strategy, Comparator<Person> {

	@Override
	public void sort(List<Person> list) {
		Collections.sort(list, this);
	}
	@Override
	public int compare(Person p1, Person p2) {
		return p2.getId() - p1.getId();
	}

}

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);
	}
	
}

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());
		}

	}