Java — Multithreading

Java Threads

Threads allow a program to operate more efficiently by doing multiple things at the same time.

Threads can be used to perform complicated tasks in the background without interrupting the main program.

Creating a Thread

There are two ways to create a thread.

It can be created by extending the Thread class and overriding its run() method. Another way to create a thread is to implement the Runnable interface.

1. Creating a thread by extending Thread class

2. Creating a thread by implementing Runnable interface.

Life Cycle of a Thread

A thread goes through various stages in its life cycle. For example, a thread is born, started, runs, and then dies. The following diagram shows the complete life cycle of a thread.

Image Source: ScienceTechEasy

• New − A new thread begins its life cycle in the new state. It remains in this state until the program starts the thread. It is also referred to as a born thread.
• Runnable − After a newly born thread is started, the thread becomes runnable. A thread in this state is considered to be executing its task.
• Waiting − Sometimes, a thread transitions to the waiting state while the thread waits for another thread to perform a task. A thread transitions back to the runnable state only when another thread signals the waiting thread to continue executing.
• Timed Waiting − A runnable thread can enter the timed waiting state for a specified interval of time. A thread in this state transitions back to the runnable state when that time interval expires or when the event it is waiting for occurs.
• Terminated (Dead) − A runnable thread enters the terminated state when it completes its task or otherwise terminates.