计算当前运行得线程数量

1.ThreadGroup

System.out.println("hello"); ThreadGroup group = Thread.currentThread().getThreadGroup(); ThreadGroup topGroup = group; while (group != null) { topGroup = group; group = group.getParent(); } //找到顶级得线程组 int nowThreads = topGroup.activeCount();// 获取对应active 线程数量 Thread[] lstThreads = new Thread[nowThreads]; topGroup.enumerate(lstThreads); for (int i = 0; i < nowThreads; i++) { System.out.println("线程number：" + i + " = " + lstThreads[i].getName()); }

topGroup.enumerate(lstThreads); enumerate方法用来将ThreadGroup线程组中的active线程全部复制到Thread类型的数组中，并且返回数组中元素个数，即线程组中active线程数量。 enumerate方法详解

2.MXBean方式

System.out.println("below is thread info:"); ThreadMXBean threadMXBean = ManagementFactory.getThreadMXBean(); long[] threadIds = threadMXBean.getAllThreadIds(); ThreadInfo[] threadInfos = threadMXBean.getThreadInfo(threadIds); for (ThreadInfo threadInfo : threadInfos) { System.out.println(threadInfo.getThreadId()+": "+threadInfo.getThreadName()); }

3.打断点方式查看