array

Scala FAQ: How do I find the unique items in a List, Array, Vector, or other Scala sequence?

Use the distinct method. Here's a simple example using a List of integers:

scala> val x = List(1,1,1,2,2,3,3)
x: List[Int] = List(1, 1, 1, 2, 2, 3, 3)

scala> x.distinct
res0: List[Int] = List(1, 2, 3)

As you can see, res0 now contains only the unique elements in the list.

Scala Array FAQ: How do I merge two Arrays or ArrayBuffers?

Solution: Use the ++ method to join two arrays into one new array:

scala> val a = Array(1,2,3)
a: Array[Int] = Array(1, 2, 3)

scala> val b = Array(4,5,6)
b: Array[Int] = Array(4, 5, 6)

scala> val c = a ++ b
c: Array[Int] = Array(1, 2, 3, 4, 5, 6)

ArrayBuffer

Use the same approach to merge two ArrayBuffers into a new ArrayBuffer:

Scala/XPath FAQ: How do I get the first element of an array in an XML document using Scala and XPath?

I ran into the problem of needing to get the first array element from an XML document using Scala and XPath recently, and in short, I ended up writing some Scala/XPath code that looked like this:

If you ever need to generate a list of subdirectories in a directory in Scala, here's one way to do it:

def getListOfSubDirectories(directoryName: String): Array[String] = {
  return (new File(directoryName)).listFiles.filter(_.isDirectory).map(_.getName)
}

I intentionally wrote that function in a short, "Scala like" style, but you can expand it to multiple lines, if you prefer.

To demonstrate the use of this directory-listing function, you can print all your subdirectories like this:

Scala array FAQ: How do I create a String array in Scala?

There are a few different ways to create String arrays in Scala. If you know all your array elements initially, you can create a Scala string array like this:

val fruits = Array("Apple", "Banana", "Orange")

If you don't know the strings that you want in your array initially, but know the size of your array, you can create it first, then populate it later, like this: