用java写一段程序，一块蛋糕有30g，两只蚂蚁轮流搬蛋糕，一只蚂蚁一次可以搬走2g，蚂蚁A搬走6g后蚂蚁B才开始搬，用多线程模拟两只蚂蚁搬完所有的蛋糕

好的，以下是代码实现：

public class AntCake {

    private static final int CAKE_WEIGHT = 30;
    private static final int ANT_CAPACITY = 2;

    private static int cakeWeight = CAKE_WEIGHT;

    public static void main(String[] args) {
        Thread antA = new Thread(() -> {
            int count = 0;
            while (cakeWeight > 0) {
                synchronized (AntCake.class) {
                    if (count < 3) {
                        if (cakeWeight >= ANT_CAPACITY) {
                            cakeWeight -= ANT_CAPACITY;
                            System.out.println("蚂蚁A搬走了" + ANT_CAPACITY + "g，还剩" + cakeWeight + "g");
                            count++;
                            AntCake.class.notify();
                        } else {
                            try {
                                AntCake.class.wait();
                            } catch (InterruptedException e) {
                                e.printStackTrace();
                            }
                        }
                    } else {
                        AntCake.class.notify();
                        break;
                    }
                }
            }
        });

        Thread antB = new Thread(() -> {
            while (cakeWeight > 0) {
                synchronized (AntCake.class) {
                    if (cakeWeight >= ANT_CAPACITY) {
                        cakeWeight -= ANT_CAPACITY;
                        System.out.println("蚂蚁B搬走了" + ANT_CAPACITY + "g，还剩" + cakeWeight + "g");
                        AntCake.class.notify();
                    } else {
                        try {
                            AntCake.class.wait();
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                }
            }
        });

        antA.start();
        antB.start();
    }
}

程序中使用了两个线程分别模拟两只蚂蚁，使用了synchronized同步代码块和wait/notify机制来保证两只蚂蚁交替搬运蛋糕的顺序和保证线程安全。其中蚂蚁A在搬运前需要等待蚂蚁B搬运完一定数量的蛋糕后才能开始搬运，因此使用了一个计数器count来控制。同时当蛋糕数量为0时，线程退出。