Java: 使用信号量(Semaphore)保护多个共享资源的访问(2)

private void reclaimPrinter(Printer p) {
        lock.lock();
        this.freePrinters[p.getIndex()] = true;
        lock.unlock();
    }

}

最后编写测试代码，启动10个线程请求使用打印机：

// create printer pool
        PrinterPool pool = new PrinterPool();

Runnable job = () -> {
            pool.printData();
        };

// create 10 threads
        Thread[] threads = new Thread[10];
        for (int ix = 0 ; ix < 10 ; ++ix) {
            threads[ix] = new Thread(job);
        }

// start all threads
        for (int ix = 0 ; ix < 10 ; ++ix) {
            threads[ix].start();
        }

输出结果：