使用JAVA代码完成以下题目 1.定义一个品牌计算机的枚举类，里面只有固定的几个计算机品牌，例如：Lenovo、HP、Dell、Apple、Acer 2.定义四个行线程操作，两个线程执行减操作，两个线程执行加操作

1. 定义品牌计算机的枚举类

public enum ComputerBrand {
    LENOVO,
    HP,
    DELL,
    APPLE,
    ACER
}

2. 定义四个线程类，两个线程执行减操作，两个线程执行加操作

class AddThread implements Runnable {
    private int value = 0;
    private Object lock = new Object();

    public void run() {
        while (true) {
            synchronized (lock) {
                value++;
                System.out.println(Thread.currentThread().getName() + " add value: " + value);
            }
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

class SubThread implements Runnable {
    private int value = 0;
    private Object lock = new Object();

    public void run() {
        while (true) {
            synchronized (lock) {
                value--;
                System.out.println(Thread.currentThread().getName() + " sub value: " + value);
            }
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

3. 创建主线程，启动四个子线程

public class Main {
    public static void main(String[] args) {
        Thread addThread1 = new Thread(new AddThread(), "AddThread1");
        Thread addThread2 = new Thread(new AddThread(), "AddThread2");
        Thread subThread1 = new Thread(new SubThread(), "SubThread1");
        Thread subThread2 = new Thread(new SubThread(), "SubThread2");

        addThread1.start();
        addThread2.start();
        subThread1.start();
        subThread2.start();
    }
}