I copied some Java code and Android Studio automat...

# announcements

[Joe]

I copied some Java code and Android Studio automatically converted it for me, but fit doesn’t seem to work and my grasp of generics in Kotlin isn’t strong enough to understand why.

Here’s the Java:

if (!(raw instanceof Map)) {
    ...
}

And here’s the converted Kotlin:

if (raw !is Map<*, *>) {
   ...
}

Now the variable raw is actually of type LinkedHashTreeMap which inherits from Map. What am I missing?

[ilya.gorbunov]

What error do you get?

[Joe]

No error, it’s is true (meaning that raw isn’t a Map).

[Joe]

Sorry, that was important information. 🙂

[ilya.gorbunov]

Does LinkedHashTreeMap inherit from java.util.Map?

[Joe]

I believe so. LinkedHashTreeMap extends AbstractMap, which in turn implements Map.

[Joe]

Sorry, I didn’t realize that LinkedHasTreeMap wasn’t from the standard Java library. But yes, Map is the ultimate interface.

[Shawn]

sounds like some guava tomfoolery

[Joe]

Moshi, actually.

[Shawn]

ahh gotcha

[Joe]

To be specific, raw looks like this at runtime:

raw = {LinkedHashTreeMap@7019}  size = 3
 0 = {LinkedHashTreeMap$Node@7026} "data" -> " size = 3"
 1 = {LinkedHashTreeMap$Node@7027} "data_type" -> "current_power"
 2 = {LinkedHashTreeMap$Node@7028} "data_id" -> "84b1a48c-44df-4e80-bfaf-ffe024846126"

[ilya.gorbunov]

Then there should not be difference between Kotlin an Java code. The former compiles to INSTANCEOF java/util/Map check and then going to the branch if the result is false.

[Joe]

Huh, now it’s working! Honestly, I sometimes think the compiler waits until I post a question to start working just so it can embarrass me. 🤦 Thanks for your help anyway!