monitors.java

public class DeadlockDemo {
    static class MonitorA {
        synchronized void callB(MonitorB b) {
            String t = Thread.currentThread().getName();
            Thread.sleep(100);
            b.fromA();
        }

        synchronized void fromB() {
            String t = Thread.currentThread().getName();
        }
    }

    static class MonitorB {
        synchronized void callA(MonitorA a) {
            String t = Thread.currentThread().getName();
            Thread.sleep(100);
            a.fromB(); 
        }

        synchronized void fromA() {
            String t = Thread.currentThread().getName();
        }
    }

    public static void main(String[] args) throws Exception {
        MonitorA a = new MonitorA();
        MonitorB b = new MonitorB();

        Thread t1 = new Thread(() -> a.callB(b), "T1");
        Thread t2 = new Thread(() -> b.callA(a), "T2");

        t1.start();
        t2.start();

        t1.join(2000);
        t2.join(2000);
    }
}