java 查看只有main函數的類，啓動了幾個線程

public class OnlyMain {
    public static void main( String[] args ) {
        //Java 虛擬機線程系統的管理接口
        ThreadMXBean threadMXBean = ManagementFactory.getThreadMXBean();
        //不需要獲取同步monitor 和 synchronize信息，僅僅獲取線程和線程堆棧信息
        ThreadInfo[] threadInfos = threadMXBean.dumpAllThreads(false,false);
        //遍歷線程信息，僅僅打印線程ID和線程名稱信息
        for(ThreadInfo threadInfo:threadInfos){
            System.out.println("["+threadInfo.getThreadId()+"]"+threadInfo.getThreadName());
        }
    }
}

結果如下:

[6]Monitor Ctrl-Break
[5]Attach Listener
[4]Signal Dispatcher
[3]Finalizer
[2]Reference Handler
[1]main