Scala For Loop Syntax

For Loop with Counter

The simplest loop syntax is:

for (a  <- 1 to 5){
   println(“Print a: ” + a);
}




When the above code is compiled and executed, it produces following result:

Print a: 1
Print a: 2
Print a: 3
Print a: 4
Print a: 5

By default, counter increment is 1. You can change the number of counter increment using "by".

for (a  <- 1 to 5 by 2) {
   println(“Print a: ” + a);
}

When the above code is compiled and executed, it produces following result:

Print a: 1
Print a: 3
Print a: 5

For Loop with Filter

You can filter out some of the elements. Following is the example of for loop along with filters:

for (
   a  <- 1 to 5
   if ( a > 3)
) {
   println(“Print a: ” + a);
}

When the above code is compiled and executed, it produces following result:

Print a: 4
Print a: 5

For Loop with Yield

This is one of the awesome feature in Scala where you generate a static type variable using loop. I don’t really see in other programming language.

When For loop finishes running, it returns a collection of all these yielded values.

The type of the collection that is returned is the same type that you were iterating over.

// Loop through and generate a variable
val i = for (
   a  <- 1 to 5
   if ( a > 3)
) yield {
   a
}

// Print the result
for( a <- i){
   println( "Value of a: " + a );
}

When the above code is compiled and executed, it produces following result:

Print a: 4
Print a: 5