java获取所有的线程信息

public class T2 {

public static void main(String[] args) {

Thread[] tt = findAllThreads();
for(Thread t: tt){
System.out.println(t.getId()+"\t "+t.getName());
}
}

public static Thread[] findAllThreads() {
ThreadGroup group =
Thread.currentThread().getThreadGroup();
ThreadGroup topGroup = group;

        // 遍历线程组树，获取根线程组
while ( group != null ) {
topGroup = group;
group = group.getParent();
}
        // 激活的线程数加倍
int estimatedSize = topGroup.activeCount() * 2;
Thread[] slackList = new Thread[estimatedSize];
        //获取根线程组的所有线程
int actualSize = topGroup.enumerate(slackList);
// copy into a list that is the exact size
Thread[] list = new Thread[actualSize];
System.arraycopy(slackList, 0, list, 0, actualSize);
return list;
}
}