java 多线程之 implements Callable

• 线程的实现方式

  • java 多线程之 extends Thread

  • java 多线程之 implements Runnable

  • java 多线程之 implements Callable

• 线程池的使用

  • 线程池简介

  • ThreadPoolExecutor

    • java 线程池之 newScheduledThreadPool

    • java 线程池之 newCachedThreadPool

    • java 线程池之 newFixedThreadPool

    • java 线程池之 newSingleThreadExecutor

  • ForkJoinPool

    • java 线程池之 newWorkStealingPool

实现Callable接口主要是可以获取到返回值,futureTask.get() 获取返回的值

示例代码：

public class ThreadImplCallable implements Callable {
    /**
     * 线程名称
     */
    private String threadName;

    /**
     * 构造函数
     *
     * @param threadName 线程名称
     */
    public ThreadImplCallable(String threadName) {
        this.threadName = threadName;
    }
    /**
     * 重写call方法
     */
    @Override
    public T call() throws Exception {
        System.out.println(threadName);
        return (T)threadName;
    }
}

public class ThreadMain {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        Callable threadImplCallable = new ThreadImplCallable<>("Thread1");
        FutureTask futureTask = new FutureTask<>(threadImplCallable);
        Thread thread = new Thread(futureTask);
        thread.start();
        String rValue = futureTask.get();
        System.out.println("Thread1 return value is " + rValue);
        threadImplCallable = new ThreadImplCallable<>("Thread2");
        futureTask = new FutureTask<>(threadImplCallable);
        thread = new Thread(futureTask);
        thread.start();
        rValue = futureTask.get();
        System.out.println("Thread2 return value is " + rValue);

        System.out.println("end");
    }
}

结果：

Thread1
Thread1 return value is Thread1
Thread2
Thread2 return value is Thread2
end