设计一个有getMin(),push(),pop().功能的栈

package chapter01_stack_and_queue;

import java.util.Stack;

public class _01_GetMinStack {
public static class MyStack {
Stack<Integer> stackData = new Stack<Integer>();
Stack<Integer> stackMin = new Stack<Integer>();

/**
* 申请另外一个栈一直存储最小值。与数据栈同步增长push
* @param newNum
*/
public void push(int newNum) {
if (this.stackMin.isEmpty()) {
this.stackMin.push(newNum);
} else if (newNum < this.getMin()) {
this.stackMin.push(newNum);
} else {
int newMin = this.stackMin.peek();
this.stackMin.push(newMin);
}
this.stackData.push(newNum);
}

public int pop() {
this.stackMin.pop();
return this.stackData.pop();
}

private int getMin() {
return this.stackMin.peek();
}
}

public static void main(String[] args) {
MyStack stack = new MyStack();
stack.push(3);
stack.push(4);
stack.push(1);
System.out.println(stack.getMin());
stack.pop();
System.out.println(stack.getMin());
}
}