java 线程实例，单线程，多线程

//: ThreadInfo.java public class ThreadInfo{ public static void main(String[] args){ Thread[] threads = new Thread[4]; ThreadGroup tGroup = new ThreadGroup("MyThreadGroup"); if( args.length > 0) { Thread aThread = Thread.currentThread(); aThread.setName(args[0]); } for ( int i=0; i<4; i++ ) { threads[i] = new Thread(tGroup,"MyThread#" + i); threads[i].start(); } ThreadInfo.printAllThreadInfo(); } // list information about all the threads and threads and // in the application public static void printAllThreadInfo(){ ThreadGroup parent,root; // find the root of all runngin threads root = parent = Thread.currentThread().getThreadGroup(); while((parent = parent.getParent()) != null) root = parent; // print information recursively from the root System.out.println(); printThreadGroupInfo("",root); } // print information about a thread group public static void printThreadGroupInfo(String indent, ThreadGroup tGroup){ if ( tGroup == null ) return; System.out.println(indent + "Thread Group:" + tGroup.getName() + ";Max Priority: " + tGroup.getMaxPriority() + (tGroup.isDaemon()?"[Daemon]":"")); // print information about component threads int no_of_threads = tGroup.activeCount(); Thread[] threads = new Thread[no_of_threads]; no_of_threads = tGroup.enumerate(threads,false); for ( int i=0; i<no_of_threads; i++ ) printThreadInfo(indent + " " , threads[i]); // print information about component thread groups int no_of_groups = tGroup.activeGroupCount(); ThreadGroup[] groups = new ThreadGroup[no_of_groups]; no_of_groups = tGroup.enumerate(groups,false); for ( int i=0; i<no_of_groups; i++ ) printThreadGroupInfo(indent+" ", groups[i]); } public static void printThreadInfo(String indent, Thread aThread){ if ( aThread == null ) return; System.out.println(indent + "Thread: " + aThread.getName() + ";Priority: " + aThread.getPriority() + (aThread.isDaemon()?"[Daemon]":"") + (aThread.isAlive()?"[Alive]":"")); } }