multthreedemo.java

Java 程序设计源码 只提供了部分

interface InterfNumList {
	int getNextNum();
	void setFirstNum();
	void pointNum(int x);
}

class MultThree implements InterfNumList {
	int start;
	int val;
	int prev;
	
	public MultThree() {
		start = 1;
		val = 1;
		int prev = -3;	
	}

	public int getNextNum() {
		prev = val;
		val *= 3;

		return val;
	}

	public void setFirstNum() {
		start = 1;
		val = 1;
		prev = -3;
	}

	public void pointNum(int x) {
		start = x;
		val = x;	
		prev = x - 3;
	}

	public int getPrevNum() {
		return prev;
	}
}

class MultFour implements InterfNumList {
	int start;
	int val;
	int prev;
	
	public MultFour() {
		start = 1;
		val = 1;
		int prev = -4;	
	}

	public int getNextNum() {
		prev = val;
		val *= 4;

		return val;
	}

	public void setFirstNum() {
		start = 1;
		val = 1;
		prev = -4;
	}

	public void pointNum(int x) {
		start = x;
		val = x;	
		prev = x - 4;
	}

	public int getPrevNum() {
		return prev;
	}
}

public class MultThreeDemo {
	public static void main(String[] args) {
		MultThree mt = new MultThree();
	
		for(int i = 0; i < 4; i++)
			System.out.println(mt.getNextNum());

		System.out.println();

		mt.setFirstNum();
		
		for(int i = 0; i < 4; i++)
			System.out.println(mt.getNextNum());	

		System.out.println();
		
		System.out.println("starting at 10:");
		
		mt.pointNum(10);

		for(int i = 0; i < 4; i++)
			System.out.println(mt.getNextNum());	
		System.out.println(mt.getPrevNum());

		//instance of MultFour
		System.out.println("MultFour:");

		MultFour mf = new MultFour();
	
		for(int i = 0; i < 4; i++)
			System.out.println(mf.getNextNum());

		System.out.println();

		mf.setFirstNum();
		
		for(int i = 0; i < 4; i++)
			System.out.println(mf.getNextNum());	

		System.out.println();
		
		System.out.println("starting at 10:");
		
		mf.pointNum(10);

		for(int i = 0; i < 4; i++)
			System.out.println(mf.getNextNum());	
		System.out.println(mf.getPrevNum());
	}
}