Why is void used?

[Vishal Hegde]

This might sound a bit weird but i really did not get the void concept in book it's given that void is a return type which returns nothing then why to use void?

[Campbell Ritchie]

The void keyword is not so much a erturn type as an absence of return type.

It is needed because every method must declare what it returns, or (void) that it returns nothing.

[Ashish Tiwari]

Campbell Ritchie wrote:The void keyword is not so much a erturn type as an absence of return type.

Exactly what Campbell says. I just want to give you an example that gives the clear understanding of void. In swing/AWT (It could be true for any other Java frameworks. I tested it in Swing/AWT. So, please conside this). For an analogy, We have simple user login page. In this page we are first checking whether user filled username and password or not? If
No then we will simply put a check

  if(userTextField hasnot correctValue){ //#1
return ; // here we do not need to return anything since method has void return type (or nothing to return). 
}  

else yes then

Create Database Connection

Validate User

And other related user authentication task

So in first check (#1) we say to compiler if something goes wrong then please do not proceed further.

I think that will be sufficient to explain. In case of any doubt please let me know.

[Campbell Ritchie]

I would have thought that throwing an Exception would be a better approach than a plain return; statement in that situation.

[Janeice DelVecchio]

I just had to do a whole project that was filled with entry validation. I didn't throw any exceptions, just returned true or false for good or bad. It seems like Ashish had a similar take on a similar problem. I guess now that you say it exceptions might be good, but I think in a beginner or low level school project, probably not necessary.

[Campbell Ritchie]

If I were marking, I would give extra marks for your using Exceptions to enforce defensive programming.

[John de Michele]

I agree with Campbell that exceptions are a much better choice.

John.

[Ashish Tiwari]

John de Michele wrote:I agree with Campbell that exceptions are a much better choice.

John.

I also agree with Campbell's comments but I just want to give a glimpse of void returning situations. It is always as good practice to handle exception rather than simply writing return.

[Vinod Tiwari]

Say you senerio where you want to do some action but don't want to have an acknowledgement (read return) you can use a void there.