兩個線程交替列印奇數和偶數

實作思路是使用鎖來控制不同線程的執行。下面有兩種實作：

1、使用對象螢幕：

public class OddEvenPrinter {

    private final Object monitor = new Object();
    private final int limit;
    private volatile int count;

    public OddEvenPrinter(int limit, int initCount) {
        this.limit = limit;
        this.count = initCount;
    }

    public void print() {
        synchronized (monitor) {
            while (count < limit) {
                try {
                    System.out.println(String.format("線程[%s]列印數字:%d", Thread.currentThread().getName(), ++count));
                    monitor.notifyAll();
                    monitor.wait();
                } catch (InterruptedException e) {
                    //ignore
                }
            }
        }
    }

    public static void main(String[] args) throws Exception {
        OddEvenPrinter printer = new OddEvenPrinter(10, 0);
        Thread thread1 = new Thread(printer::print, "thread-1");
        Thread thread2 = new Thread(printer::print, "thread-2");
        thread1.start();
        thread2.start();
        Thread.sleep(Integer.MAX_VALUE);
    }
}      

public class OddEvenPrinterEx {

    private final ReentrantLock lock = new ReentrantLock();
    private final Condition condition = lock.newCondition();

    private final int limit;
    private volatile int count;

    public OddEvenPrinterEx(int limit, int initCount) {
        this.limit = limit;
        this.count = initCount;
    }

    public void print()  {
        lock.lock();
        try {
           while (count < limit){
               System.out.println(String.format("線程[%s]列印數字:%d", Thread.currentThread().getName(), ++count));
               condition.signalAll();
               try {
                   condition.await();
               } catch (InterruptedException e) {
                   //ignore
               }
           }
        } finally {
            lock.unlock();
        }
    }

    public static void main(String[] args) throws Exception {
        OddEvenPrinterEx printer = new OddEvenPrinterEx(10, 0);
        Thread thread1 = new Thread(printer::print, "thread-1");
        Thread thread2 = new Thread(printer::print, "thread-2");
        thread1.start();
        thread2.start();
        Thread.sleep(Integer.MAX_VALUE);
    }
}