02_ranges.adoc

Extensions to IntegerRange

IntegerRange is a handy type from the Xtend standard library which can be constructed using the .. operator. But the only way to iterate over the elements of the range is by boxing the integers while iterating.

The extensions provided by this library allow iterating over the primitive values of the range.

One way to iterate over the range is to use Java 8 streams, by using the stream or parallelStream extension method from the class de.fhg.fokus.xtensions.range.RangeExtensions.

Exmaple:

import static extension de.fhg.fokus.xtensions.range.RangeExtensions.*
// ...
val range = (0..20).withStep(2)
range.stream.filter[it % 5 == 0].sum

Another way to iterate over the elements of a range is to use the forEachInt method.

Example:

import static extension de.fhg.fokus.xtensions.range.RangeExtensions.*
// ...
val range = (0..20).withStep(2)
range.forEachInt [
	println(it)
]

To interact with consumers expecting an IntIterable (see Primitive Iterables), which is a generic interface for iteration over primitive int values provided by this library, the extension method asIntIterable was provided.

Tip	Related JavaDocs: RangeExtensions