1、setDeamon
设置线程为后台运行的函数
public class SetDaemon
{
public static void main(String[] args) throws InterruptedException
{
Thread tt=new Thread(new ThreadTest());
tt.setDaemon(true); //设置程序为后台运行
tt.start();
Thread.sleep(3);
}
}
class ThreadTest implements Runnable
{
public void run()
{
while(true)
{
System.out.println(Thread.currentThread().getName()+" is running...");
}
}
}
可见当父线程后台运行的线程自动结束。
2、join
强制CPU执行某个线程
public class SetDaemon
{
public static void main(String[] args) throws InterruptedException
{
Thread tt=new Thread(new ThreadTest());
tt.start();
for(int i=0;i<10;i++)
{
if(i==5)
{
tt.join();
}
System.out.println(Thread.currentThread().getName()+i+" is running...");
}
}
}
class ThreadTest implements Runnable
{
public void run()
{
for(int i=0;i<5;i++)
{
System.out.println(Thread.currentThread().getName()+i+" is running...");
}
}
}
3、interrupt
中断线程public class SetDaemon
{
public static void main(String[] args) throws InterruptedException
{
Thread tt=new Thread(new ThreadTest());
tt.start();
Thread.sleep(2000);
System.out.println("The subthread is interupted in the main thread.");
tt.interrupt();
tt.join();
System.out.println("The main thread is over.");
}
}
class ThreadTest implements Runnable
{
public void run()
{
try
{
System.out.println("The subthread is sleeping...");
Thread.sleep(200000);
}
catch(Exception e)
{
e.printStackTrace();
System.out.println("The subthread is interupted.");
return;
}
System.out.println("The subthread is over.");
}
}
注意:这里的线程中断和通常所讲的硬件中断并不是同一个概念,硬件中断是...(这个就不要讲啦),这里的中断可以理解成线程的状态被设置成了中断状态(即挂起了一个小旗,告诉其它线程‘哥处于中断状态’,禁止某些操作),此时执行某些函数会触发异常,被中断的线程进入到异常处理代码段。
请仔细体会以下代码:
public class SetDaemon
{
public static void main(String[] args) throws InterruptedException
{
Thread tt=new Thread(new ThreadTest());
tt.start();
Thread.sleep(5);
System.out.println("The subthread is interupted in the main thread.");
tt.interrupt();
tt.join();
System.out.println("The main thread is over.");
}
}
class ThreadTest implements Runnable
{
public void run()
{
try
{
while(true)
{
System.out.println(Thread.currentThread().getName()+" is running...");
Thread.sleep(1);
}
}
catch(Exception e)
{
e.printStackTrace();
System.out.println("The subthread is interupted.");
return;
}
//System.out.println("The subthread is over.");
}
}
可以使用isInterupt()查看线程是否被中断。