Design a special stack, on the basis of realizing the basic functions of the stack, and then realize the operation of returning the smallest element in the stack

import java.util.Stack;

/**
 * 设计一个特殊的栈，在实现栈的基本功能的基础上，再实现返回栈中最小元素的操作
 * @author 21405
 *
 */
public class SpecialStack {
    private Stack<Integer> stackData;
    private Stack<Integer> stackMin;

    public SpecialStack(){
        this.stackData = new Stack<Integer>();
        this.stackMin = new Stack<Integer>();

    }

    /**
     * 入栈
     * <p> stackData 用作普通的栈，stackMin用作存最小值的栈
     * @throws Exception 
     */
    public void push(int A) throws Exception{

        if(stackData.isEmpty() && stackMin.isEmpty()){
            stackData.push(A);
            stackMin.push(A);
        }else{
            if(A < getMin()){
                stackMin.push(A);
                stackData.push(A);
            }else{
                stackData.push(A);
            }
        }


    }
  /**
   * 出栈 
 * @throws Exception 
   */
    public int pop() throws Exception{
        if(stackData.peek() == getMin()){
             stackMin.pop();

        }
        return stackData.pop();
    }

    /**
     * 获取最小值
     * @throws Exception 
     */
    public int getMin() throws Exception{
        if(this.stackMin.isEmpty()){
            throw new Exception("Stack is empty");
        }
        return stackMin.peek();
    }


}