堆栈 先进后出源码 升级版

案例出自于：java编程参考官方教程   150页

package com.chinadays.learn;

public class Stack {

	private int stack[];

	int tos;

	public Stack(int length) {

		stack = new int[length];
		this.tos = -1;
	}

	void push(int item) {
		if (item >= stack.length)
			System.out.println("Stack is full!");

		else
			stack[++tos] = item;
	}

	int pop() {
		if (tos < 0) {
			System.out.println("Stack underflow");
			return 0;
		} else
			return stack[tos--];
	}

}

　　

使用方法：

package com.chinadays.learn;

public class TestStack {
	public static void main(String[] args) {
		Stack st1 = new Stack(10);

		Stack st2 = new Stack(20);

		for (int i = 0; i < 10; i++)
			st1.push(i);

		for (int i = 0; i < 20; i++)
			st2.push(i);

		for (int i = 0; i < 10; i++)
			System.out.println(st1.pop());

		for (int i = 0; i < 20; i++)
			System.out.println(st2.pop());

	}
}

　　

运行 结果：

9
8
7
6
5
4
3
2
1
0
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0