package chapter_stack_and_queue; import java.util.*; public class stack { public static void main(String[] args) { /* 初始化栈 */ Stack stack = new Stack<>(); /* 元素入栈 */ stack.push(1); stack.push(3); stack.push(2); stack.push(5); stack.push(4); System.out.println("栈 stack = " + stack); /* 访问栈顶元素 */ int peek = stack.peek(); System.out.println("栈顶元素 peek = " + peek); /* 元素出栈 */ int pop = stack.pop(); System.out.println("出栈元素 pop = " + pop + ",出栈后 stack = " + stack); /* 获取栈的长度 */ int size = stack.size(); System.out.println("栈的长度 size = " + size); /* 判断是否为空 */ boolean isEmpty = stack.isEmpty(); } }