stack containing min function

Set up an auxiliary stack. Whenever an element is placed in the stack, the current minimum value is also placed in the auxiliary stack;
whenever the stack is popped, the current value and the current minimum value are simultaneously popped out of the stack. The code is as follows :

import java.util.Stack;

public class Solution {

    Stack<Integer> stack = new Stack();
    Stack<Integer> minStack = new Stack();

    public void push(int node) {
        stack.push(node);
        if(minStack.isEmpty() || node < minStack.peek()){
            minStack.push(node);
        }else{
            minStack.push(minStack.peek());
        }
    }

    public void pop() {
        stack.pop();
        minStack.pop();
    }

    public int top() {
        return stack.peek();
    }

    public int min() {
        return minStack.peek();
    }
}

Reference:
https://blog.csdn.net/jsqfengbao/article/details/47260355
https://blog.csdn.net/u012289407/article/details/46564841