music5.java

java的容器应用

//: Music5.java
// Interfaces
import java.util.*;

interface Instrument5 {
	// Compile-time constant:
	int i = 5; // static & final
	// Cannot have method definitions:
	void play(); // Automatically public
	String what();
	void adjust();
}

class Wind5 implements Instrument5 {
	public void play() {
		System.out.println("Wind5.play()");
	}
	public String what() { return "Wind5"; }
		public void adjust() {}
	}
	class Percussion5 implements Instrument5 {
		public void play() {
		System.out.println("Percussion5.play()");
	}
	public String what() { return "Percussion5"; }
	public void adjust() {}
}

class Stringed5 implements Instrument5 {
	public void play() {
		System.out.println("Stringed5.play()");
	}
	public String what() { return "Stringed5"; }
	public void adjust() {}
}

class Brass5 extends Wind5 {
	public void play() {
		System.out.println("Brass5.play()");
	}
	public void adjust() {
		System.out.println("Brass5.adjust()");
	}
}

class Woodwind5 extends Wind5 {
	public void play() {
		System.out.println("Woodwind5.play()");
	}
	public String what() { return "Woodwind5"; }
}

public class Music5 {
	// Doesn't care about type, so new types
	// added to the system still work right:
	static void tune(Instrument5 i) {
		// ...
		i.play();
	}
	static void tuneAll(Instrument5[] e) {
		for(int i = 0; i < e.length; i++)
			tune(e[i]);
	}
	public static void main(String[] args) {
		Instrument5[] orchestra = new Instrument5[5];
		int i = 0;
		// Upcasting during addition to the array:
		orchestra[i++] = new Wind5();
		orchestra[i++] = new Percussion5();
		orchestra[i++] = new Stringed5();
		orchestra[i++] = new Brass5();
		orchestra[i++] = new Woodwind5();
		tuneAll(orchestra);
	}
} ///:~