ReentrantLock test

ReentrantLockTest.java

    private void test() {
        final LockTest test = new LockTest();

        new Thread(new Runnable() {
            @Override
            public void run() {
                test.lockTest();
                //                test.readLockTest();
                //                test.writeLockTest();
            }
        }, "AAA").start();

        new Thread(new Runnable() {
            @Override
            public void run() {
                test.lockTest();
                //                test.readLockTest();
                //                test.writeLockTest();
            }
        }, "BBB").start();
    }

    class LockTest {
        private ReentrantLock lock = new ReentrantLock();
        private ReentrantReadWriteLock rwLock = new ReentrantReadWriteLock();

        public void lockTest() {
            lock.lock();
            try {
                System.out.println(Thread.currentThread().getName() + " start");
                Thread.sleep(5000);
                System.out.println(Thread.currentThread().getName() + " end");
            } catch (Exception e) {
            } finally {
                lock.unlock();
            }
        }

        public void readLockTest() {
            rwLock.readLock();
            try {
                System.out.println(Thread.currentThread().getName() + " start");
                Thread.sleep(5000);
                System.out.println(Thread.currentThread().getName() + " end");
            } catch (Exception e) {
            } finally {
                rwLock.readLock().unlock();
            }
        }

        public void writeLockTest() {
            rwLock.writeLock();
            try {
                System.out.println(Thread.currentThread().getName() + " start");
                Thread.sleep(5000);
                System.out.println(Thread.currentThread().getName() + " end");
            } catch (Exception e) {
            } finally {
                rwLock.writeLock().unlock();
            }
        }
    }

• ReentrantLock
  lock中は別スレからlock不可
• ReentrantReadWriteLock
  別スレでlock(read/write)中の lock取得(read/write) は可能。
  ただ、lock解放はlock時と同じスレッドで行う必要あり。
  別スレで解放すると以下の例外発生。

java.lang.IllegalMonitorStateException:
attempt to unlock read lock, not locked by current thread