The JVM threads are the Operating System threads. Java wraps an underlying OS thread as an instance of the java.lang.Thread class, and builds up an API around it to work with threads. A thread on the JVM has a number of states: New, Runnable, Blocked, Waiting, Timed_Waiting, and Terminated. A thread is instantiated by overriding the run() method of the Thread class, or by passing an instance of the java.lang.Runnable interface to the constructor of the Thread class.

Invoking the start() method of a Thread instance starts its execution in a new thread. Even if just a single thread runs in the JVM, the JVM would not shut down. Calling the setDaemon(boolean) method of a thread with argument true tags the thread as a daemon that can be automatically shut down if no other non...