helloworld程序会创建几个线程-

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import java.lang.management.ManagementFactory;
import java.lang.management.ThreadInfo;
import java.lang.management.ThreadMXBean;
/**
 * 执行一个hello world 需要几个线程?
 * 1.Attach Listener
 * 2.Signal Dispatcher:    
 * 3.Finalizer:
 * 4.Reference Handler:
 * 5.main:
 * @author User
 *
 */
public class DefaultThread {
	private final static ThreadMXBean mBean = ManagementFactory.getThreadMXBean();

	public static void main(String[] args) {
		System.out.println("hello world");
		long[] allThreadIds = mBean.getAllThreadIds();
		ThreadInfo[] threadInfo = mBean.getThreadInfo(allThreadIds);
		for (ThreadInfo info : threadInfo) {
			System.out.print(info.getThreadName() + ":\t");
			System.out.println(info.getThreadState());
		}
	}
}