java 栈

栈一次只允许访问一个数据项：即最后插入的数据项。移除这个数据项后才能访问倒数第二个数据项，依此类推。栈的数据项遵循后进先出的次序。
1.栈的实现代码

package com.gjy.stack;


public class Stack {
	private int maxSize;
	private char [] stackArray;
	private int top;

	public Stack(int s){
		maxSize = s;
		stackArray = new char[maxSize];
		top = -1;
	}

//      添加数据
	public void push(char j){
		stackArray[++top] = j;
	}

//      删除数据
	public char pop(){
		return stackArray[top--];
	}

//      获取数据
	public char peek(){
		return stackArray[top];
	}

//      判断栈是否为空
	public boolean isEmpty(){
		return (top == -1);
	}

//      判断栈是否已满
	public boolean isFull(){
		return (top ==  maxSize-1);
	}

}

下面以一个输入字符串的倒序输出为例：

package com.gjy.stack;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Reverser {
	private String input;
	private String output;

	public Reverser(String in){
		input = in;
	}

	public String doRve(){
		int stackSize = input.length();
		Stack stack = new Stack(stackSize);

		for(int i=0;i<input.length();i++){
			char c = input.charAt(i);
			stack.push(c);
		}

		output = "";

		while(!stack.isEmpty()){
			char c = (char) stack.pop();
			output = output + c;
		}

		return output;
	}

	public static void main(String[] args) {
		String input,output;

		while (true) {
			System.out.println("Enter a String: ");
			BufferedReader buf=new BufferedReader(new InputStreamReader(System.in));
			try {
				input = buf.readLine();

				if ("".equals(input.trim())||input==null){
					break;
				}

				Reverser reverser = new Reverser(input);
				output = reverser.doRve();
				System.out.println(output);
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}
}