Which is better, a `val` with a backing property, ...

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[Vishnu Haridas]

Which is better, a val with a backing property, or a public property with a private setter? Is there any difference?

For example,

class Foo {

    // (1) - public property with a private setter
    var isSyncing = false
        private set
    
    // (2) - val with a backing property
    private var isSyncing_ = false
    val isSyncing get() = isSyncing_
}

[hallvard]

Did you check with javap?

[Vishnu Haridas]

I did a decompile from Kotlin Bytecode to Java in Android Studio. Both (1) and (2) are same.

[hallvard]

🙂

[Vishnu Haridas]

Just checking if there is any preference for one style over the other? 🤔

[Stephan Schroeder]

hmm, i always did (2) but (1) is probabaly nicer in that it communicates that the value you get isn’t immutable.

[Stephan Schroeder]

(2) is more efficient though, because a private property is actually converted to a Java field. So it can be accessed from within the class without going through getters and setters.

[Burkhard]

That is only really true for android without any of the optimizations of the jvm. final getters within the same class should just be optimized to a field access.

[Burkhard]

I personally prefer (1). It is less work to write and it shows a clearer intend. The advantage of (2) is that the backing field can have a different type eg. public get List and private MutableList