public class CustomRentrantLock {

    public static void main(String[] args) {
        LockCustom LockCustom=new ReentrantLockCustom();
        MyRunnable myRunnable=new MyRunnable(LockCustom);
        new Thread(myRunnable,"Thread-1").start();
        new Thread(myRunnable,"Thread-2").start();
    }
}

class MyRunnable implements Runnable{

    LockCustom lockCustom;
    public MyRunnable(LockCustom LockCustom) {
        this.lockCustom=LockCustom;
    }

    public void run(){
        System.out.println(Thread.currentThread().getName() +" is Waiting to acquire LockCustom");
        lockCustom.lock();
        System.out.println(Thread.currentThread().getName() +" has acquired LockCustom.");
        try {
            Thread.sleep(5000);
            System.out.println(Thread.currentThread().getName() +" is sleeping.");
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println(Thread.currentThread().getName() +" has released LockCustom.");
        lockCustom.unlock();
    }
}

interface LockCustom {
    void lock();
    void unlock();
    boolean tryLock();
}

class ReentrantLockCustom implements LockCustom {
    int lockHoldCount;
    long lockingThreadId;

    ReentrantLockCustom() {
        lockHoldCount = 0;
    }

    public synchronized void lock() {
        if (lockHoldCount == 0) {
            lockHoldCount++;
            lockingThreadId = Thread.currentThread().getId();
        } else if (lockHoldCount > 0 && lockingThreadId == Thread.currentThread().getId()) {
            lockHoldCount++;
        } else {
            try {
                wait();
                lockHoldCount++;
                lockingThreadId = Thread.currentThread().getId();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    public synchronized void unlock() {
        if (lockHoldCount == 0)
            throw new IllegalMonitorStateException();
        lockHoldCount--;
        if (lockHoldCount == 0)
            notify();
    }


    public synchronized boolean tryLock() {
        if (lockHoldCount == 0) {
            lock();
            return true;
        } else
            return false;
    }
}