Android Development with Kotlin

Labeled returns in lambda expressions

Let's look at a case in which we need to return from a lambda expression and not from a function. We can do this using labels. Here is an example of a return from a lambda expression using labels:

    inline fun <T> forEach(list: List<T>, body: (T) -> Unit) { // 1 
        for (i in list) body(i) 
    } 
 
    fun printMessageButNotError(messages: List<String>) { 
        forEach(messages) messageProcessor@ { // 2 
            if (it == "ERROR") return@messageProcessor // 3 
            print(it) 
        } 
    } 
 
    // Usage 
    val list = listOf("A", "ERROR", "B", "ERROR", "C") 
    processMessageButNotError(list) // Prints: ABC 

1. This is a generic implementation of the forEach function, where a list with any type can be processed.
2. We define a label for the lambda expression inside ...