LambdaDemo.java

public class LambdaDemo {
  
  public static void withLock(ReentrantLock lock, Runnable run) {
      if(lock == null || run == null){
      throw new IllegalArgumentException("lock or run must not be null.");
      }
      lock.lock();
      try {
        run.run();
      } finally {
        lock.unlock();
      }
  }

}