How to Stop Thread in Java Code Example

The thread is one of important Class in Java and multithreading is most widely used a feature,but there is no clear way to stop Thread in Java. Earlier there was a stop method exists in Thread Class but Java deprecated that method citing some safety reason. By default, a Thread stops when execution of run() method finish either normally or due to any Exception.In this article, we will How to Stop Thread in Java by using a boolean State variable or flag. Using a flag to stop Thread is a very popular way  of stopping the thread and it's also safe because it doesn't do anything special rather than helping run() method to finish itself.

How to Stop Thread in Java

As I said earlier Thread in Java will stop once run() method finished. Another important point is that you can not restart a Thread which run() method has finished already , you will get an IllegalStateExceptio, here is a Sample Code for Stopping Thread in Java.

Sample Code to Stop Thread in Java

private class Runner extends Thread{

boolean bExit = false;

public void exit(boolean bExit){

this.bExit = bExit;

}

@Override

public void run(){

while(!bExit){

System.out.println("Thread is running");

try {

Thread.sleep(500);

} catch (InterruptedException ex) {

Logger.getLogger(ThreadTester.class.getName()).log(Level.SEVERE, null, ex);

}

}

}

}

Should we make bExit Volatile

Since every thread has its own local memory in Java its good practice to make bExit volatile because we may alter the value of bExit from any thread and make it volatile guarantees that Runner will also see any update done before making bExit.

That’s all on how to stop the thread in Java, let me know if you find any other way of stopping threads in Java without using deprecated stop() method.

Further Learning

Multithreading and Parallel Computing in Java

Java Concurrency in Practice - The Book

Applying Concurrency and Multi-threading to Common Java Patterns

Java Concurrency in Practice Course by Heinz Kabutz

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