Kotlin Program to Join Two Lists

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Joining two lists is a common operation in many programming scenarios. In Kotlin, this task can be accomplished using various methods, each with its unique advantages and applications. This article will explore three different Kotlin Program to Join Two Lists, including detailed explanations, code implementations, and outputs for each example.

1. Using the + Operator

1.1 Program Explanation

The simplest way to join two lists in Kotlin is by using the + operator. This operator concatenates two lists and returns a new list containing all the elements of the original lists.

1.2 Code Implementation

Kotlin
fun main() {
    val list1 = listOf("Apple", "Banana", "Cherry")
    val list2 = listOf("Date", "Elderberry", "Fig")

    // Join lists using the + operator
    val joinedList = list1 + list2

    println("List 1: $list1")
    println("List 2: $list2")
    println("Joined List: $joinedList")
}

1.3 Output

Kotlin
List 1: [Apple, Banana, Cherry]
List 2: [Date, Elderberry, Fig]
Joined List: [Apple, Banana, Cherry, Date, Elderberry, Fig]

2. Using the addAll Method

2.1 Program Explanation

The addAll method is used to add all elements from one list to another. This method is typically used with mutable lists like ArrayList.

2.2 Code Implementation

Kotlin
fun main() {
    val list1 = arrayListOf("Apple", "Banana", "Cherry")
    val list2 = listOf("Date", "Elderberry", "Fig")

    // Join lists using the addAll method
    list1.addAll(list2)

    println("Joined List: $list1")
}

2.3 Output

Kotlin
Joined List: [Apple, Banana, Cherry, Date, Elderberry, Fig]

3. Using the union Function

3.1 Program Explanation

The union function creates a set containing all distinct elements from both lists. This method is useful when you want to join two lists while removing duplicates.

3.2 Code Implementation

Kotlin
fun main() {
    val list1 = listOf("Apple", "Banana", "Cherry", "Apple")
    val list2 = listOf("Date", "Elderberry", "Fig", "Banana")

    // Join lists using the union function
    val joinedSet = list1.union(list2)

    println("List 1: $list1")
    println("List 2: $list2")
    println("Joined Set: $joinedSet")
}

3.3 Output

Kotlin
List 1: [Apple, Banana, Cherry, Apple]
List 2: [Date, Elderberry, Fig, Banana]
Joined Set: [Apple, Banana, Cherry, Date, Elderberry, Fig]

Conclusion

In this article, we explored three different methods to join two lists in Kotlin. The first example demonstrated how to use the + operator to concatenate two lists, resulting in a new list containing all the elements of both lists. The second example used the addAll method to add all elements from one list to another mutable list, which is especially useful when working with ArrayList. The third example showcased the union function to join two lists into a set containing all distinct elements, which is helpful for removing duplicates.

Each method offers different advantages depending on the specific requirements of your program. By understanding these techniques, you can effectively manage and manipulate collections in your Kotlin projects.