Why is this thread affecting the main thread?

Question

I must be missing something: ``` public class Test { public static void main(String[] args) { (new Thread(new Action())).run(); System.out.println("Blah"); } } class Action implements Runnable { public void run() { while (true) { } } } ``` I make a thread that is supposed to be running a loop. In my main thread I print "Blah". However, it is never printed. Why not? If I made a separate thread, it shouldn't affect my main execution thread, right? This machine has four cores.

Accepted Answer

Call `start()` instead of `run()` to start a thread.

Simply calling `run()` means a method call with infinite loop in the same `main` thread that will block the next statement written in `main` thread.

Have a look at Java Tutorial on Defining and Starting a Thread

I should be `(new Thread(new Action())).start();` to start a thread but still it will create an infinite loop and the new started thread will never stop.

Try with `Thread.currentThread().getName()` to confirm it again as shown below:

```
public void run() {
    System.out.println(Thread.currentThread().getName()); // output "main"
}
```

A Pictorial Representation of Thread Life-cycle along with it's methods

Why is this thread affecting the main thread?

Solution

Problem