特点：先进后出，后进先出

创建初始化类

public class MyStack {

    int[] elements;
    
    public MyStack() {
        elements = new int[0];
    }
    
    public void showStack() {
        System.out.println("栈中所有元素:"+Arrays.toString(elements));
    }
}

栈的相关操作

压栈

 public void push(int element) {
       //创建一个新数组
       int[] newArr = new int[elements.length+1];
       for (int i = 0; i < elements.length; i++) {
           newArr[i] = elements[i];
       }
       //把新元素添加进数组中
       newArr[elements.length] = element;
       //把新数组赋给原来的数组
       elements = newArr;
   }

弹栈(取出栈顶元素)

public int pop() {
    //判断栈中是否有元素
    if(elements.length == 0) {
        throw new RuntimeException("Stack is empty");
    }
    int element = elements[elements.length-1];
    //创建一个新数组用来替换原来的数组(因为弹栈之后数组长度要改变)
    int[] newArr = new int[elements.length-1];
    for (int i = 0; i < newArr.length; i++) {
        newArr[i] = elements[i];
    }
    //把新数组赋给原来的数组
    elements = newArr;

    return element;
}

查看栈顶元素(不弹出)

public int peek() {
   //栈中没有元素
   if(elements.length==0) {
       throw new RuntimeException("stack is empty");
   }
   return elements[elements.length-1];
}

判断栈是否为空

public boolean isEmpty() {
	return elements.length==0;
}

测试

public class TestMyStack {
  public static void main(String[] args) {
       MyStack myStack = new MyStack();
        //向栈中压入三个元素
        myStack.push(33);
        myStack.push(44);
        myStack.push(55);
        myStack.showStack(); //查看栈中所有元素
        System.out.println("取出栈顶元素:"+ myStack.pop());
        System.out.println("取出栈顶元素:"+ myStack.pop());
        myStack.showStack(); //查看栈中所有元素
   }
}

测试结果为：