java.lang.ThreadGroup[name=main,maxpri=10] java.lang.ThreadGroup[name=system,maxpri=10] main 10 false java.lang.ThreadGroup[name=system,maxpri=10] null system 10 false main: [Thread[main,5,main]] [] system: [Thread[FinalizerDaemon,5,system], Thread[FinalizerWatchdogDaemon,5,system], Thread[HeapTaskDaemon,5,system], Thread[ReferenceQueueDaemon,5,system], Thread[Signal Catcher,5,system]] [java.lang.ThreadGroup[name=main,maxpri=10]] art.Test925$CustomThreadGroup[name=TEST GROUP,maxpri=10] java.lang.ThreadGroup[name=main,maxpri=10] TEST GROUP 10 false