import java.util.concurrent.locks.ReadWriteLock; import java.util.concurrent.locks.ReentrantReadWriteLock; public class Main { public static void main(String[] args) { System.out.println("read to write test"); ReadWriteLock lock = new ReentrantReadWriteLock(); lock.readLock().lock(); // get our own read lock lock.writeLock().lock(); // upgrade to write lock System.out.println("passed"); } }