import java.util.*;

enum Node{
	MIDDLE_C,C_SHARP,B_FLAT
}

interface Instructment{
	public void play(Node n);
	public void adjust();
}

class Winds implements Instructment{
	public void play(Node n){
		System.out.println(this+".play() "+n);
	}
	public String toString(){
		return "Winds";
	}
	public void adjust(){
		System.out.println(this+".adjust()");
	}
}

 class Percussion implements Instructment{
	 public void play(Node n){
		 System.out.println(this+".play() "+n);
	 }   
	 public String toString(){
		 return "Percussion";
	 }
	 public void adjust(){
		 System.out.println(this+".adjust()");
	 }
 }

 class Stringed implements Instructment{
	 public void play(Node n){
		 System.out.println(this+".play() "+n);
	 }   
	 public String toString(){
		 return "Stringed";
	 }
	 public void adjust()
	 {
		 System.out.println(this+".adjust()");
	 }
 }

 class Brass extends Winds{
	 public String toString(){
		 return "Brass";
	 }
}

 class WoodWinds extends Winds{
	 public String toString(){
		 return "WoodWinds";
	 }
 }

public class Music2{
	public static void tune(Instructment i){
		i.play(Node.MIDDLE_C);
	}
	
	static void tuneAll(Instructment[] e){
		for(Instructment i:e)
			tune(i);
	}

	public static void main(String[] args){
		Instructment[] e={
			new Winds(),
			new Percussion(),
			new Stringed(),
			new Brass(),
			new WoodWinds()
			};
		tuneAll(e);
	}
}

多重继承：如果要从一个非接口的类继承，那么只能从一个类继承，其余的基元素都必须是接口，需要将所有的接口名都置于implements关键字之后，用逗号将它们一一隔开。可以继承任意多个接口，并可以向上转型为每个接口，因为每个接口都是一个独立的类型。

import java.util.*;

interface CanFight{
	void fight();
}

interface CanSwim{
	void swim();
}

interface CanFly{
	void fly();
}

class ActionCharacter{
	public void fight(){
		System.out.println("Fight");
	}
}

class Hero extends ActionCharacter
	implements CanFight,CanSwim,CanFly{
		public void swim(){
			System.out.println("Swim");
		}
		public void fly(){
			System.out.println("Fly");
		}
	}

public class Adventure{
	public static void t(CanFight x){
		x.fight();
	}

	public static void u(CanSwim x){
		x.swim();
	}

	public static void v(CanFly x){
		x.fly();
	}

	public static void w(ActionCharacter x){
		x.fight();
	}

	public static void main(String[] args){
		Hero h=new Hero();
		t(h);
		u(h);
		v(h);
		w(h);
	}
}