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kotlin - Use of Boolean? in if expression

If I have a nullable Boolean b, I can do the following comparison in Java:

Boolean b = ...;
if (b != null && b) {
   /* Do something */
} else {
   /* Do something else */
}

In Kotlin, I can achieve the same by using the !! operator:

val b: Boolean? = ...
if (b != null && b!!) {
   /* Do something */
} else {
   /* Do something else */
}

However, the use of !! feels a bit sketchy to me, circumventing the null safety system.

Is there a more elegant approach for this?


Edit It seems I oversimplicated a bit. For local variables, as Banthar shows, it does work. However, my Boolean b is actually a "property with a backing field" (I'm not really up to speed yet what this imposes). This is the result:

enter image description here

See Question&Answers more detail:os

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by (71.8m points)

You can compare nullable boolean with true, false or null using equality operator:

var b: Boolean? = null
if (b == true) {
    // b was not null and equal true
} 
if (b == false) {
   // b is false 
}
if (b != true) { 
   // b is null or false 
}

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