Android Development with Kotlin

A callback after a threaded operation

If we need to do a long operation, and we don't want to make the user wait for it, then we have to start it in another thread. To be able to use a callback after a long operation called in a separate thread, we need to pass it as an argument. Here's an example function:

fun longOperationAsync(longOperation: ()->Unit, callback: ()->Unit) { 
        Thread({ // 1 
            longOperation() // 2 
            callback() // 3 
        }).start() // 4 
    }     // Usage    longOperationAsync(            longOperation = { Thread.sleep(1000L) },            callback = { print("After second") }             // 5, Prints: After second    )    println("Now") // 6, Prints: Now

1. Here, we create Thread. We also pass a lambda expression that we would like to execute on the constructor argument.
2. Here, we are ...