Reentrant Synchronised Block

package multithreading.lock;

public class ReentrantSyncrhonizedBlock{

   public synchronized void outer() throws InterruptedException {
       System.out.println(Thread.currentThread().getName() + " enters OUTER");
       Thread.sleep(500);
       inner();
   }

   private synchronized void inner() {
       System.out.println(Thread.currentThread().getName() + " enters INNER");
   }
}

package multithreading.lock;

public class ClientReentrantSynchronizedBlock {

    public static void main(String[] args) throws InterruptedException {
        ReentrantSyncrhonizedBlock reentrant = new ReentrantSyncrhonizedBlock();
        for (int i = 0; i < 5; i++) {
            new Thread(() -> {
                try {
                    reentrant.outer();
                } catch (InterruptedException e) {
                    throw new RuntimeException(e);
                }
            }, "Thread " + i).start();
        }

        Thread.sleep(7000); // needed to wait all threads to be completed (I'm lazy to call join on them after starting =) )
    }
}