[数据结构与算法]Java数据结构《栈》用单向链表模拟栈并用菜单测试

package stack;

import java.util.Scanner;

public class SingleLinkedListStackTest {
    public static void  main(String[] args) {
        SingleLinkedListStack singleLinkedListStack = new SingleLinkedListStack();
        Scanner scanner = new Scanner(System.in);
        boolean loop = true;
        String key = "";
        while(loop == true){
            System.out.println("向栈加入数据：" + "push");
            System.out.println("显示队栈中数据：" + "show");
            System.out.println("获取栈顶数据：" + "pop");
            System.out.println("退出：" + "exit");
            System.out.println("请输入你的选项：");
            key = scanner.next();
            switch (key){
                case "push":
                    System.out.println("请输入一个整数");
                    int value = scanner.nextInt();
                    singleLinkedListStack.push(value);
                    break;
                case "show":
                    singleLinkedListStack.show();
                    break;
                case "pop":
                    try {
                        System.out.println(singleLinkedListStack.pop());
                    } catch (Exception e) {
                        System.out.println(e.getMessage());
                    }
                    break;
                case "exit":
                    loop = false;
                    break;
                default:
                    System.out.println("请输入正确指令");
                    break;
            }

        }
        System.out.println("程序退出");
    }
}
class SingleLinkedListStack{
    StackNode first = null;
    int top = -1;
    
    public boolean isEmpty(){
        return top == -1;
    }
    
    public void push(int value){
        StackNode stackNode= new StackNode(value);
        if (first == null) {
            first = stackNode;
            top++;
            return;
        }
        StackNode curr = first;
        for (int i = 0; i < top; i++) {
            curr = curr.next;
        }
        curr.next = stackNode;
    }

    public int pop(){
        if (isEmpty()){
            throw new RuntimeException("栈空");
        }
        StackNode curr = first;
        for (int i = 0; i < top-1; i++) {
            curr = curr.next;
        }
        int value = curr.next.value;
        curr.next = null;
        top--;
        return value;
    }

    public void show(){
        if (isEmpty()){
            System.out.println("栈空");
            return;
        }
        for (int i = top; i >= 0; i--) {
            StackNode curr = first;
            for (int j = 0; j < i; j++) {
                curr = curr.next;
            }
            System.out.printf("第%d：%d\n",i,curr.value);
        }

    }
}
class StackNode{
    int value;
    StackNode next;

    public StackNode(int value) {
        this.value = value;
    }

    @Override
    public String toString() {
        return "StackNode{" +
                "value=" + value +
                '}';
    }
}