`Tuple`

In Scala 3.3, a tuple combines 2 or more values in a single unit. For example, we can combine a string and an integer with some simple syntax.

With tuples, we build abstractions over related values. This helps simplify many parts of our Scala programs. A function can return more than 1 value in a tuple.

First example

Here we create 2 tuples, each with 2 items. The tuples have a String and Int. We can access the first and second items in them.

Detail We can access the first and second items from a tuple with the "_1" and "_2" syntax.

Note The first item in a tuple is at index 1, not index 0, and we must use "_1" to get it.

object Program {
    def main(args: Array[String]): Unit = {
        // Create and print two tuples.
        val identity1 = ("ABC", 10)
        val identity2 = ("DEF", 20)

        println(identity1)
        println(identity2)

        // Get first and second items from a tuple.
        val first = identity1._1
        val second = identity1._2

        println(first)
        println(second)
    }
}(ABC,10)
(DEF,20)
ABC
10

Return multiple values

Often in programs we want to return multiple values from a function. Parameters, classes, or tuples may be used. Here we return a tuple from function.

Note The upperName def receives a name String and returns a two-item tuple containing the uppercase name and the original name.

object Program {
    // This def returns a two-item tuple.
    // ... It uppercases the argument String.
    def upperName(name: String): (String, String) = (name.toUpperCase(), name)

    def main(args: Array[String]): Unit = {
        // Call upperName function with String.
        val name = "scala"
        val result = upperName(name)
        println(result)
    }
}
(SCALA,scala)

Unpack

We can unpack a tuple in an assignment statement. Here the function returns a tuple with two items in it. We assign the values number1 and number2 to those items.

Tip This syntax immediately unpacks a tuple. This can make a program simpler to read.

object Program {
    // Return a tuple.
    def twoNumbers(x: Int): (Int, Int) = (x * 2, x * 4)

    def main(args: Array[String]): Unit = {
        // Unpack the tuple returned by the function.
        val (number1, number2) = twoNumbers(3)
        println(number1)
        println(number2)
    }
}6
12

`Match`

We can use a tuple as the argument of a match construct. We specify values within match cases to require specific values in a tuple.

Here The test() method receives a String, Int tuple. If the first item is "bird" the first case is matched.

object Program {
    def test(animal: (String, Int)) = {
        animal match {
            case ("bird", size) =>
                println("Bird weighs " + size)
            case (animal, size) =>
                println("Other animal " + animal + ", " + size)
        }
    }

    def main(args: Array[String]): Unit = {
        // Call test method with tuple argument.
        val animal = ("bird", 20)
        test(animal)

        val animal2 = ("cat", 300)
        test(animal2)
    }
}Bird weighs 20
Other animal cat, 300

`Tuple` list

With a list of tuples we can make a 2D array or a collection of complex elements. Here we use 3 items in each tuple and access them in a for-loop.

object Program {
    def main(args: Array[String]): Unit = {
        // Create list of tuples.
        val animals = List(("cat", 10, "yellow"), ("bird", 1, "blue"))

        // Loop over tuples.
        for (value <- animals) {
            println(value._1 + " is " + value._3)
            println("... weighs " + value._2)
        }
    }
}cat is yellow
... weighs 10
bird is blue
... weighs 1

Tuples are common in Scala. They have a simple syntax form, so we can use them with minimal effort. They combine data together, enabling manipulation of data units.

Tuple