Java Thread Sleep and Interrupted Exception

Question

1. Why does a sleep thread need a try catch to catch Interrupted Exception?
2. Why does a sleep even emit an Interrupted Exception error? This are the two questions I really wanna find out about in java programming I've been searching through google and i've still haven't found a clear explanation is to why this two things happen.

Answer 1

1. Because a Thread cant complete its normal execution if you Interrupt it, and you need to catch that in order to be prepared to do something.
2. Because a thread waiting is different from an interrupted thread, a thread waiting can be resumed, but an interrupted thread is already finish execution.

Answer 2

An InterruptedException is thrown when the thread is blocked/waiting and it is interrupted by another thread (by means of Thread.interrupt). Think of it as a request for immediate termination, that do not suffer the drawbacks of Thread.stop().

This way, even if you instruct a thread to sleep for several years, you are able to interrupt that thread.

The recommended practice is aborting whatever you are processing when a InterruptedException is thrown.