Java中多线程打印abc

public class PrintABC {
    private int state;
    private int count;
    private static final int MAX_COUNT = 50;

    public synchronized void printLetter(String letter, int targetState) {
        while (state != targetState) {
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        System.out.print(letter);

        state = (state + 1) % 3;
        count++;
        if (count == MAX_COUNT) {
            System.exit(0);
        }
        notifyAll();
    }

    public static void main(String[] args) {
        PrintABC printABC = new PrintABC();

        new Thread(() -> {
            while (printABC.count < MAX_COUNT) {
                printABC.printLetter("A", 0);
            }
        }).start();

        new Thread(() -> {
            while (printABC.count < MAX_COUNT) {
                printABC.printLetter("B", 1);
            }
        }).start();

        new Thread(() -> {
            while (printABC.count < MAX_COUNT) {
                printABC.printLetter("C", 2);
            }
        }).start();
    }
}

该代码使用一个共享的状态state，来控制3个线程按顺序交替打印"A"，"B"和"C"。每个线程在运行时会检查当前的state值，如果值不符合该线程打印的字符，则线程会进入等待状态。当状态值与线程打印的字符相同时，线程会打印字符，并通知其他线程来唤醒等待。在打印完指定次数后，程序通过调用System.exit()方法来结束程序。