Thread JDK1.5

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一、Java5 前时代

1. 并发实现（两种）

Java Green Thread (模拟线程实现方式。)

Java Native Thread

2. 局限性

缺少线程管理的支持。（线程池）
缺少“锁”API。
缺少执行完成的状态。
执行结果获取困难。
Double Check locking 不确定性。

3. Code 例子

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public class ThreadMain {
    public static void main(String[] args) {
        Thread thread = new Thread(new Runnable() {
            /**
             * synchronized 关键字是是一种编程语言修饰符。
             * */
            @Override
            public synchronized void run() {
                System.out.printf("[Thread : %s] Hello , World... \n",Thread.currentThread().getName());
            }
        },"Sub");

        thread.start();
        System.out.printf("[Thread : %s] Starting......\n",Thread.currentThread().getName());
    }
}
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/**
 * 可完成的{@link Runnable}
 *
 * @author Yangkai
 * @create 2018-10-24-12:11
 */
public class CompletableRunnableMain {
    public static void main(String[] args) throws InterruptedException {
        CompletableRunnable completableRunnable = new CompletableRunnable();
        Thread thread = new Thread(completableRunnable, "Sub");

        thread.start();
        /**
         * Waits for this thread to die.
         * 等着线程执行结束。串行操作。
         **/
        thread.join();
        System.out.printf("[Thread : %s] Starting......\n", Thread.currentThread().getName());

        System.out.printf("running is completed .....: %s\n", completableRunnable.isCompleted());
    }

    private static class CompletableRunnable implements Runnable {
        private volatile boolean completed = false;

        @Override
        public void run() {
            System.out.printf("[Thread : %s] Hello , World... \n", Thread.currentThread().getName());
            completed = true;
        }

        public boolean isCompleted() {
            return completed;
        }
    }
}