Java：Callable

1、具體實現

1. 創建 FutureTask 輔助類 MyCallable 實現 Callable 接口。
2. 創建 MyCallable 對象：MyCallable myCallable = new MyCallable()。
3. 創建 線程輔助類 FutureTask 對象：FutureTask futureTask = new FutureTask(myCallable)。
4. 創建線程對象：Thread thread1 = new Thread(futureTask, “線程一”)。
5. 調用線程對象的 start() 方法。

public class CallableDemo {
    
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        MyCallable myCallable = new MyCallable();
        FutureTask<Integer> futureTask = new FutureTask(myCallable);
        FutureTask<Integer> futureTask2 = new FutureTask(myCallable);
        Thread thread1 = new Thread(futureTask, "線程一");
        Thread thread2 = new Thread(futureTask2, "線程二");
        thread1.start();
        thread2.start();

        Integer integer1 = futureTask.get();
        Integer integer2 = futureTask2.get();
        System.out.println("最後剩餘票數爲:" + integer1 + "," + integer2);
    }

    static class MyCallable implements Callable<Integer> {

        // 100 張票
        private static int ticket = 100;

        @Override
        public Integer call() throws Exception {

            while (ticket > 1) {
                ticket--;
                System.out.println(Thread.currentThread() + "賣掉了1張票，剩餘票數爲:" + ticket);

                Thread.sleep(200L);
            }

            return ticket;
        }
    }
}

線程實現	特點
繼承 Thread	單繼承，無返回值
實現 Runnable	可以多實現，無返回值
實現 Callable	可以多實現，有返回值