Scala Tuple

Scala Collections

Like lists, tuples are also immutable, but unlike lists, tuples can contain elements of different types.

The value of a tuple is composed by enclosing individual values in parentheses. For example:

val　t　=　(1,　3.14, "Fred")

The above examples define three elements in the tuple, with corresponding types [Int, Double, java.lang.String].

In addition, we can also define in the following way:

val　t　=　new　Tuple3(1,　3.14, "Fred")

The actual type of a tuple depends on the type of its elements, for example (99, "w3codebox") is Tuple2[Int, String]. ('u', 'r', "the", 1, 4, "me") is Tuple6[Char, Char, String, Int, Int, String].

Currently, Scala supports the maximum length of tuples as 22. For greater lengths, you can use a set or extend the tuple.

Accessing elements of a tuple can be done through numeric indices, as in the following tuple:

val　t　=　(4,3,2,1)

We can use t._1 Access the first element, t._2 Access the second element as shown below:

object　Test　{
　　　def　main(args:　Array[String])　{
　　　　　　val　t　=　(4,3,2,1)
　　　　　　val　sum　=　t._1　+　t._2　+　t._3　+　t._4
　　　　　　println(　"Sum of elements is:　"　　+　sum　)
　　　}
}

Execute the above code, the output result is:

$　scalac　Test.scala　
$　scala　Test
Sum of elements is:　10

Iterate over tuple

You can use Tuple.productIterator() methods to iterate and output all elements of a tuple:

object　Test　{
　　　def　main(args:　Array[String])　{
　　　　　　val　t　=　(4,3,2,1)
　　　　　　
　　　　　　t.productIterator.foreach{　i　=>println("Value　=　"　+　i　)}
　　　}
}

Execute the above code, the output result is:

$　scalac　Test.scala　
$　scala　Test
Value　=　4
Value　=　3
Value　=　2
Value　=　1

Tuple to String

You can use Tuple.toString() methods that combine all elements of a tuple into a single string, as shown in the following example:

object　Test　{
　　　def　main(args:　Array[String])　{
　　　　　　val　t　=　new　Tuple3(1,　"hello",　Console)
　　　　　　
　　　　　　println("The concatenated string is:　"　+　t.toString()　)
　　　}
}

Execute the above code, the output result is:

$　scalac　Test.scala　
$　scala　Test
1,hello,scala.Console$@4dd8dc3)

element swapping

You can use Tuple.swap methods to swap the elements of tuples. Here is an example:

object　Test　{
　　　def　main(args:　Array[String])　{
　　　　　　val　t　=　new　Tuple2("www.google.com",　"www.oldtoolbag.com")
　　　　　　
　　　　　　println("Swapped tuple:　"　+　t.swap　)
　　　}
}

Execute the above code, the output result is:

$　scalac　Test.scala　
$　scala　Test
Swapped tuple:　(www.oldtoolbag.com,www.google.com)

Scala Collections