java ReentrantLock

线程同步工具。可以替代 synchronized .

    private final ReentrantLock reentrantLock = new ReentrantLock();void testTask1 () {reentrantLock.lock();  // 获取锁try {System.out.println(Thread.currentThread().getName() + " 进入临界区");// 模拟执行业务逻辑Thread.sleep(100);} catch (InterruptedException e) {e.printStackTrace();} finally {reentrantLock.unlock();  // 别忘记手动释放锁System.out.println(Thread.currentThread().getName() + " 释放锁");}}static void testReentrantLock(MyClass demo) {// 启动多个线程测试for (int i = 0; i < 5; i++) {new Thread(demo::testTask1).start();}}

打印结果：

ok

另外，ReentrantLock还可以和条件变量（Condition）配合，实现线程间协调，可代替wait()/notify() ，代码略