What is the purpose of the replace() function in programming?

The replace() function is used to replace part of a string or characters with others. In Android (and in Java/Kotlin), it allows replacing all occurrences of a specific substring with a new one. For example, if you need to replace all spaces with underscores:

val original = "Hello World"
val replaced = original.replace(" ", "_") // Hello_World

This is useful for processing text data, formatting, or cleaning strings.