Android Development with Kotlin

Combination of named arguments and lambda expressions

Using default named arguments and lambda expressions can be really useful in Android. Let's look at some practical Android examples. Let's suppose we have a function that downloads elements and shows them to the user. We will add a few parameters:

• onStart: This will be called before the network operation
• onFinish: This will be called after the network operation

fun getAndFillList(onStart: () -> Unit = {},     onFinish: () -> Unit = {}){ 
        // code 
    } 

Then, we can show and hide the loading spinner in onStart and onFinish:

    getAndFillList( 
        onStart = { view.loadingProgress = true } , 
        onFinish = { view.loadingProgress = false } 
    ) 

If we start it from swipeRefresh, then we just need to hide it ...