栈得实现

 先入后出 子弹的弹夹   出栈pop  入栈push  递归调用

 

 

 

 

 

 

用数组实现栈

class ArrayStackDemo{
    public static void main(String[] args) {
        ArrayStack stack = new ArrayStack(4);
        String key = "";
        boolean loop = true;//控制是否退出菜单
        Scanner scanner = new Scanner(System.in);
        while (loop){
            System.out.println("show:表示现实栈");
            System.out.println("exit:退出程序");
            System.out.println("push:入栈");
            System.out.println("pop:出栈");
            key = scanner.next();
            switch (key){
                case "show":
                    stack.list();
                    break;
                case "pop":

                    try {
                        int res = stack.pop();
                        System.out.println("取出来的数据"+res);
                    } catch (Exception e) {
                        System.out.println(e.getMessage());
                    }
                    break;
                case "push":
                    System.out.println("请输入一个数");
                    int value = scanner.nextInt();
                    stack.push(value);
                    break;
                case "exit":
                    scanner.close();
                    loop = false;
                    break;
                default:
                    break;
            }
            System.out.println("程序退出");
        }
    }
}
/**
 * 数组模拟栈的
 * 使用数组
 * 定义一个top 表示栈顶, 初始化-1, 入栈的操作,当有数据加入到栈,top++,stack[top] = data
 * 出栈的操作,int
 */
public class ArrayStack {
    private int maxSize;//栈的大小
    private  int[] stack;//数组,数组模拟栈,数据就放在该数组
    int top = -1;//栈顶, 初始化-1 没有数据

    public ArrayStack(final int maxSize) {
        this.maxSize = maxSize;
        stack = new int[this.maxSize];
    }
    //栈满,
    public boolean isFull(){
        return top == maxSize-1;
    }
    //栈空
    public boolean isEmpty(){
        return  top == -1;
    }
    public void push(int value){
        if(isFull()){
            System.out.println("栈满");
            return;
        }
        top++;
        stack[top] = value;
    }
    //返回栈顶数据 top--;
    public int pop(){
        if(isEmpty()){
            System.out.println("空了");
//            return -1;
            throw  new RuntimeException("栈空");
        }
        int value = stack[top];
        top--;
        return value;
    }
    //遍历栈  遍历时需要从栈顶开始现实数据
    public void list(){
        if(isEmpty()){
            System.out.println("栈空,没有数据");
            return;
        }
        for (int i = top; i >= 0 ; i--) {
            System.out.printf("stack[%d]=%d\n",i,stack[i]);
        }
    }

}