import java.util.concurrent.*;
import java.util.concurrent.locks.*;

public class TestLock {
    public static void main(String[] args) {
        ExecutorService executor = Executors.newCachedThreadPool();
        LockSample ls = new LockSample();
        executor.execute(() -> ls.func());
        executor.execute(() -> ls.func());
        executor.shutdown();
    }
}

class LockSample {
    private Lock lock = new ReentrantLock();

    public void func() {
        lock.lock();
        try {
            for (int i = 0; i < 5; i++) {
                System.out.println(i);
                Thread.sleep(10);
            }
        } catch (Exception e) {
        } finally {
            lock.unlock();
        }
    }
}