Kotlin allows you to define functions as members of existing classes. These are called extension functions, and they are a great way to encapsulate boilerplate code that otherwise might be repeated many times.
- [Instructor] Kotlin allows you to define…and add functions to existing classes.…These are called extension functions…and they're a great way to encapsulate boilerplate code…that otherwise might have to be repeated many times.…You can define extension functions anywhere,…including in independent files.…I'll go to my base package in this project…and I'll create a new Kotlin file…that I'll name Extensions,…and I won't turn it into a class.…Now, to declare a function, I'll use the keyword fun…and then I'll start with the class…that I'm adding the function to.…
I'm going to add this to the view class from android.view.…Now, I can name my function and I'll call it flipVisibility.…The goal of this function is…to examine the current visibility setting…for a view that is a visual widget and then change it.…So, if it's visible, I'll make it invisible,…and if it's invisible, I'll make it visible.…I'll use some simple conditional logic.…I'll say if this.visibility…equals the constant View.VISIBLE,…then I want to make it invisible.…
Skill Level Intermediate
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