//使用数组来构建stack
class stackInArray{
    
    private Object[] array;//数组
    private int stackBottom ;//stack的底部指向array的地步array[0]
    private int stackTop ;//stack的底部指向array的地步array[0]
    
    
    public stackInArray(Object[] o ){
        this.array = o;//指向构造的数组当作stakc的内存
        this.stackBottom = 0;
        this.stackTop = 0;
    }
    
    //出栈
    public Object stackPop() {
        Object o = null;
        if(stackTop == 0) {
            System.out.println("内存已空，无法出数据");
        }
        else {
            stackTop--;
            o = array[stackTop];
        }
        return o;
    }
    
    //进栈
    public void stackPush(Object o) {
        if(stackTop == array.length) {
            System.out.println("内存已满，无法存入");
            return ;
        }
        else {
            array[stackTop] = o;
            stackTop++;
        }
    }
}