📌 Lists in Kotlin

In Kotlin, a List is a collection that stores a sequence of elements. Lists are ordered and allow duplicate values. Kotlin provides two types of lists:

1. Immutable List (List) → Read-only (cannot be modified).

2. Mutable List (MutableList) → Can be modified (add, remove, or update elements).

✅ 1. Immutable List

• Created using listOf().

• Cannot be changed once initialized.

📌 Example:

kotlin
fun () {    val fruits = listOf("Apple", "Banana", "Cherry")    println(fruits)    println("First fruit: ${fruits[0]}")    println(Total Fruits: 3

• listOf() creates a read-only list.

• Access elements using the index (fruits[0]).

• Use size to get the number of elements.

✅ 2. Mutable List

• Created using mutableListOf().

• Allows adding, removing, and modifying elements.

📌 Example:

kotlin
fun () {    val numbers = mutableListOf(1, 2, 3)    numbers.add(4)                     // Add element    numbers.remove(2)                  // Remove element    numbers[0] = 10                    // Update element    println(numbers)}

Output:

csharp
[10, 3, 4]

• add() → Adds an element.

• remove() → Removes a specific element.

• numbers[0] = 10 → Updates the element at index 0.

✅ 3. List Functions in Kotlin

✅ 4. Iterating Through a List

You can iterate through a list using different methods:

📌 Using For Loop:

kotlin
fun () {    val colors = listOf("Red", "Green", "Blue")    for (color in colors) {        println(color)    }}

📌 Using ForEach:

kotlin
colors.forEach { color -> println(color) }

📌 Using Indices:

kotlin
for (index in colors.indices) {    println("Color at index $index is ${colors[index]}")}

✅ 5. Filtering and Sorting Lists

Kotlin provides powerful functions to manipulate lists:

📌 Filter:

kotlin
val numbers = listOf(1, 2, 3, 4, 5, 6)val evenNumbers = numbers.filter { it % 2 == 0 }println(evenNumbers) // Output: [2, 4, 6]

📌 Sort:

kotlin
val names = listOf("John", "Alice", "Bob")val sortedNames = names.sorted()println(sortedNames) // Output: [Alice, Bob, John]

📌 Map:

kotlin
val nums = listOf(1, 2, 3)val squaredNums = nums.map { it * it }println(squaredNums) // Output: [1, 4, 9]

✅ 6. Combining Lists

You can combine lists using different methods:

📌 Using Plus (+) Operator:

kotlin
val list1 = listOf(1, 2, 3)val list2 = listOf(4, 5, 6)val combinedList = list1 + list2println(combinedList) // Output: [1, 2, 3, 4, 5, 6]

✅ 7. Conclusion

• Use listOf() for immutable lists.

• Use mutableListOf() for mutable lists.

• Apply functions like filter(), map(), and sorted() for manipulation.

• Iterate using loops or forEach.

• Combine lists using the + operator.