Kotlin ternary operator

Question

How can I convert the following code from Java to Kotlin?

Boolean mBoolean = false
view.setVisibility(mBoolean ? View.VISIBLE : View.GONE);

Android Studio can convert the code for you. If the problem you have is with the ternary expression, then the equivalent construct in kotlin is `if else`. — Michael, Feb 20 '19 at 14:45

A.Bitner · Accepted Answer · 2019-02-20T14:52:02.067

13

val mBoolean = false
view.visibility = if(mBoolean) View.VISIBLE else View.GONE

However I doubt it makes any sense to make mBoolean immutable here, so instead of val mBoolean I'd go with var mBoolean.

edited Feb 20 '19 at 14:52

answered Feb 20 '19 at 14:47

A.Bitner

191
1
5

`var` would be the correct translation since `mBoolean` isn't `final` in the Java code. – Michael Feb 20 '19 at 14:48
1

It is always better to use `val` in Kotlin. For example, there are some features, like smart cases that would work with `val` and not with `var` declarations – Eugene Petrenko Feb 20 '19 at 15:09

score 0 · Answer 2 · answered Feb 20 '19 at 14:49

You can epannd on view.visibility = if(mBoolean) View.VISIBLE else View.GONE by creating extension function

fun View.makeVisible(show:Boolean){
    this.visibilility = if(show) View.VISIBLE else View.GONE   
}


var mBolean = false
view.makeVisible(mBoolean)

score 0 · Answer 3 · answered Feb 20 '19 at 15:23

0

You can also use when operator:

 val mBoolean = false
        view.visibility = when (mBoolean) {
            true -> View.VISIBLE
            false -> View.GONE
        }

answered Feb 20 '19 at 15:23

Nicola Gallazzi

7,897
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Kotlin ternary operator

3 Answers3