This is a short Scala post to explain what the difference is between val and var. I was showing some Scala code to a co-worker this past week and he was asking what the difference was between val and var. It is quite simple:

val defines a fixed value, it is a read only variable
var defines a mutable variable, this variable can be modified

In Java you would use final to create a variable which would be read only, this is the same as val in Scala.

Let's look at some very simple Scala code.

Running the code above will give the following output
Test1 5
Test1 6
done with main

If you are trying to use val, you will get an error, change var to val and see if you can compile the code

Here is the error, the code won't even compile

Description		Resource	Path		Location	Type
reassignment to val	Test.scala	/ScalaTemp/src	line 8		Scala Problem

So as you can see, val is read only, while with var you can modify the variable.

If you want to play around with Scala, take a look at Installing Scala 2.10 on Eclipse Juno