Learn kotlin - extension function

Extend the functionality

What is extended functionality ？

seeing the name of a thing one thinks of its function , Extension functions are functions that help us extend the functions of classes without touching their code .

let me put it another way ,Kotlin The extension function in allows us to extend the function of the class by adding new functions . This class doesn't have to belong to us （ It can be a third-party library ）, We don't need to inherit this class .

Take a very simple example to understand .

fun Int.triple(): Int {
  return this * 3
}

// now we can use like this
var result = 3.triple()

Another example , Let's see how Android View Use it in .

fun ImageView.loadImage(url: String) {
    Glide.with(context).load(url).into(this)
}

// now we can use like this
imageView.loadImage(url)

It looks great ！

stay Android There are many places in the development , We can use Kotlin This cool feature . Let's use this powerful function when we need it .