music4.java

翁剀JAVA语言那门课程的教案 很多人都看多他的视频教程可惜没有ppt的教案

//: Music4.java
// Abstract classes and methods
import java.util.*;

abstract class Instrument4 {
	int i; // storage allocated for each
	public abstract void play();
	public String what() {
		return "Instrument4";
	}
	public abstract void adjust();
}

class Wind4 extends Instrument4 {
	public void play() {
		System.out.println("Wind4.play()");
	}
	public String what() { return "Wind4"; }
	public void adjust() {}
}

class Percussion4 extends Instrument4 {
	public void play() {
		System.out.println("Percussion4.play()");
	}
	public String what() { return "Percussion4"; }
	public void adjust() {}
}

class Stringed4 extends Instrument4 {
	public void play() {
		System.out.println("Stringed4.play()");
	}
	public String what() { return "Stringed4"; }
	public void adjust() {}
}

class Brass4 extends Wind4 {
	public void play() {
		System.out.println("Brass4.play()");
	}
	public void adjust() {
		System.out.println("Brass4.adjust()");
	}
}

class Woodwind4 extends Wind4 {
	public void play() {
		System.out.println("Woodwind4.play()");
	}
	public String what() { return "Woodwind4"; }
}

public class Music4 {
	// Doesn't care about type, so new types
	// added to the system still work right:
	static void tune(Instrument4 i) {
		// ...
		i.play();
	}
	static void tuneAll(Instrument4[] e) {
		for(int i = 0; i < e.length; i++)
			tune(e[i]);
	}
	public static void main(String[] args) {
		Instrument4[] orchestra = new Instrument4[5];
		int i = 0;
		// Upcasting during addition to the array:
		orchestra[i++] = new Wind4();
		orchestra[i++] = new Percussion4();
		orchestra[i++] = new Stringed4();
		orchestra[i++] = new Brass4();
		orchestra[i++] = new Woodwind4();
		tuneAll(orchestra);
	}
} ///:~