In programming, we call functions to perform a particular task. The best thing about function is that we can call it any number of times and it return some value after computation i.e. if we are having add() function then it always returns the sum of both the numbers entered.
But, functions has some limitations like function return only one value at a time. If there is need to return more than one value of different data type, then we can create a class and declare all the variables that we want to return from the function and after that create an object of the class and easily collect all the returned values in a list. The main problem is that if there are so many functions in the program which returns more than one value at a time then we have to create a separate class for all those functions and finally use that class. This process increases the verbosity and complexity of the program.
In order to deal with these type of problems, Kotlin introduced the concept of Pair and Triple.
What is Triple? –
Kotlin language provides a simple datatype to store three values in a single instance. This can be done using a data class known as Triple. It is a simple generic class that stores any three values, there is no valuable meaning of the relationship between the three values. The comparison between two Triple objects is done on the basis of values, i.e. two Triples are equal only if all three component are equal.
Class Definition –
data class Pair<out A, out B, out C> : Serializable
There are three parameters:
A – type of the first value
B – type of the second value
C – type of the third value
In Kotlin, constructor is a special member function that is invoked when an object of the class is created primarily to initialize variables or properties. To create a new instance of the Triple we use:
Pair(first: A, second: B, third: C)
Kotlin example of creating triple using the constructor –
1 Geeks 2.0
We can either receive the values of triple in a single variable or we can use first,second and third properties to extract the values.
first: This field stores the first value of the Pair.
second: This field stores the second value of the Pair.
third: This field stores the third value of the Pair.
Kotlin program to retrieve the values of Triple using properties –
Hello Geeks This is Kotlin tutorial [10, 20, 30]
toString(): This function returns the string equivalent of the Triple.
fun toString(): String
Kotlin program of using the function –
String representation is (5, 5, 5) Another string representation is (Geeks, [Praveen, Gaurav, Abhi], 12345)
Extension Functions –
As we have learnt in previous articles, extension functions provides ability to add more functionality to the existing classes, by without inheriting them.
toList(): This function returns the List equivalent of the given Triple.
fun <T>Pair<T, T>.toList(): List
Kotlin program of using the extended function –
[1, 2, 3] [Hello, 2.0, [10, 20, 30]]
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