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。