layout: post

title: Threads

A __Thread__ in Java means two different things:

* An instance of class `java.lang.Thread`

* A thread of execution

An __instance of Thread__ is just an object. Like any other object in Java, it has variables and methods, and lives and

dies on the heap. But a __thread of execution__ is an individual process (a "lightweight" process) that has its own call

stack.

In Java, there is one thread per call stack or you can say, one call stack per thread. Even if you don't create any new

threads in your program, threads are back there running. The main() method, that starts the whole ball rolling, runs in

one thread, called (surprisingly) the main thread.

* Extend the `java.lang.Thread` class

* Implement the `Runnable` interface