Thread group is a collection of threads or sub thread groups

that are responsible for doing something similar and Java provides a convenient way to group multiple

threads in a single object .The advantage of using thread group is that we can perform common operation on the whole

group so in other words programmer can group the threads in thread group based on their functions to

be performed.

But ThreadGroup API is weak and it doesn’t have any functionality that is not provided by Thread.

Two of the major feature it had are to get the list of active threads in a thread group

and to set the uncaught exception handler for the thread.

So ThreadGroup is obsolete and hence not advised to use anymore.