同一个Thread启动第二次会报错java.lang.IllegalThreadStateException

先实现Thread代码

public class TestThread {

    public static void main(String[] args) {
        for (int i = 0; i < 100; i++) {
            myThread.start();
            System.out.println(myThread.getName() + "---" + i + "---");
        }

    }

    static Thread myThread = new Thread(new Runnable() {
        int count = 0;
        boolean runable = true;
        public void run() {
            while (runable) {
                count++;
                try {
                    Thread.sleep(100);
                } catch (Exception e) {

                }
                if (count > 100) {
                    runable = false;
                }
             }
        }   
    });

}

运行结果：

Thread-0---0---
Exception in thread "main" java.lang.IllegalThreadStateException
    at java.lang.Thread.start(Unknown Source)
    at TestThread.main(TestThread.java:6)

当第二次调用Thread.start()启动同一个线程时，报错。

采用Runnable实现，解决问题

public class TestRunnable {

    public static void main(String[] args) {
        for (int i = 0; i < 100; i++) {
            Thread t = new Thread(myRunnable);
            t.start();
            System.out.println( t.getName() + "---" + i + "---");
        }

    }


    static Runnable myRunnable = new Runnable() {
        int count = 0;
        boolean runable = true;

        @Override
        public void run() {
            while (runable) {
                count++;
                try {
                    Thread.sleep(100);
                } catch (Exception e) {

                }
                if (count > 100) {
                    runable = false;
                }
             }
        }
    };

}

运行结果正常。可以启动多个线程

2016/8/16修改编辑
Thread报错的原因，并不是说，重新启动Thread导致的，而是因为共用一个Thread导致的，因为，如果是实现Runnable的类，每次启动线程都需要new Thread(Runnable).start()，这就使得线程没有被共用。所以，另外一种解决办法是如下：

public class TestThread {

    public static void main(String[] args) {
        for (int i = 0; i < 100; i++) {
//          TestThread t = new TestThread();
            new TThread().start();
//          myThread.start();
//          System.out.println(myThread.getName() + "---" + i + "---");
        }
        Thread.currentThread();

    }   
}

class TThread extends Thread{
    @Override
    public void run() {
        // TODO Auto-generated method stub
        super.run();
        System.out.println("111");
    }
}

只要每次都new 一个新的线程对象，就不会报错。