1策略模式：

實現一個程式，電影票打折，老人，小孩各有不同的折扣看電影。

public class Test1 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		People p =new OldPeople("老人");
		p.buyTickets();
		p.getDiscount(new DiscontOf5());
	}

}

interface Discount{
	public void discountWay();
}

class DiscontOf7 implements Discount{
	public void discountWay(){
		System.out.println("電影票打七折");
	}
}

class DiscontOf5 implements Discount{
	public void discountWay(){
		System.out.println("電影票打五折");
	}
}

class DiscontOf8 implements Discount{
	public void discountWay(){
		System.out.println("電影票打八折");
	}
}

abstract class People{
	private String typePeople;
	private Discount discount;
	
	public People(String typePeople){
		this.typePeople=typePeople;
	}
	
	public void getDiscount(Discount discount){
		discount.discountWay();
	}
	
	public void buyTickets(){
		System.out.println(typePeople+"買票看電影！");
	}
}

class OldPeople extends People{
	public OldPeople(String typePeople){
		super(typePeople);
	}	
}
 

實現一個程式，去飯店吃飯，選擇各種不同的套餐。

public class Test {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		PersonTreat personA=new PersonA("張三");
		personA.treat();
		personA.dishes();
		personA.payment();
	}

}

abstract class PersonTreat{
	protected String name;

	public void treat(){
		System.out.println(name+"要請客吃飯");
	}
	
    public void dishes(){
    	switch (change()) {
		case 1:
			System.out.println("點的菜有：宮保雞丁，紅燒排骨。。。。。");
			break;
		case 2:
			System.out.println("點的菜有：魚香肉絲，鐵板魷魚。。。。。");
			break;
		case 3:
			System.out.println("點的菜有：碳烤活魚，水煮魚片。。。。。");
			break;
        
		default:
			System.out.println("不知道怎麼選擇。");
			break;
		}
    	
    }
    
    public void payment(){
		System.out.println(name+"結賬");
	}
    
    abstract int change();
}

class PersonA extends PersonTreat{
	public PersonA(String name) {
		this.name=name;
	}

	public int change(){
		Random r =new Random();
		int a =r.nextInt(3)+1;
		return a;
	}
   	
	
}