Converting a List to a MutableList in Kotlin

In Kotlin, the List interface represents an immutable collection of elements, while MutableList provides a collection that can be modified. There are situations where you may need to convert a List into a MutableList to perform operations like adding, removing, or updating elements. This article will guide you through the process of converting a List to a MutableList in Kotlin, with examples focused on Android development.

How to Convert a List to a MutableList

To convert a List to a MutableList, you can use the toMutableList() function provided by the Kotlin standard library. This function creates a new MutableList containing the same elements as the original List.

Here's an example:

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1val list: List<Int> = listOf(1, 2, 3, 4, 5)
2val mutableList: MutableList<Int> = list.toMutableList()
3
4mutableList.add(6)
5mutableList.remove(3)
6
7println(mutableList) // Output: [1, 2, 4, 5, 6]

In the example above, we first create a List called list containing integers from 1 to 5. We then use the toMutableList() function to convert it into a MutableList called mutableList. After the conversion, we can perform mutable operations on mutableList, such as adding element 6 and removing element 3.

Converting a List in Android Development

When working with Android development, you might often encounter scenarios where you need to convert a List to a MutableList. Let's take an example of converting a list of strings obtained from a database query into a MutableList for displaying data in a RecyclerView.

Assuming you have obtained a list of user names from a database query:

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1val userList: List<String> = getUserNamesFromDatabase()
2val mutableUserList: MutableList<String> = userList.toMutableList()

In this example, getUserNamesFromDatabase() retrieves a list of user names from a database query, which is initially returned as a List. By calling toMutableList(), we convert it into a MutableList named mutableUserList. You can now use mutableUserList to populate a RecyclerView adapter or perform any other required modification.

In Summary

Converting a List to a MutableList in Kotlin is a straightforward process using the toMutableList() function provided by the Kotlin standard library. This allows you to transform an immutable collection into a mutable one, enabling you to make changes like adding or removing elements. In Android development, converting a List to a MutableList is useful when dealing with data obtained from queries or external sources that require modification.