问题:

As I know Java is pass-by-value from this post. I am from Java background I wonder what Kotlin is using for passing values in between. Like in Extensions or Methods etc.

回答1:

Every time I hear about the "pass-by-value" vs "pass-by-reference" Java debate I always think the same. The answer I give: "Java passes a copy (pass-by-value) of the reference (pass-by-reference)". So everyone is happy. I would say Kotlin does the same as is JVM based

回答2:

The semantics is identical to Java.

In Java, when you have an instance of an object, and you pass it to a method, that method can change the state of that object, and when the method is done, the changes would have been applied to the object at the call site.

The same applies in Kotlin.

回答3:

In Java primitive types like int, float, double, boolean are passed to a method by value, if you modify them inside the receiver method they doesn't change into the calling method. But if the property/variable type isn't a primitive, like arrays of primitives or other classes when they are changed inside the method that receive them as parameter they also change in the caller method. But with Kotlin nothing seems to be primitive, so I think all is passed by reference.