Can I add Kotlin extension function to Java class?

Question

I'm trying to create extension function like this:

fun UHFTAGInfo.toReadUhfTagInfo(): ReadUhfTagInfo {
    return ReadUhfTagInfo(this.epc, this.count, this.rssi.toIntOrNull())
}

It is supposed to convert UHFTAGInfo (from java library) to ReadUhfTagInfo (my class in Kotlin).

I'm trying to use it like this:

UHFTAGInfo i = getUHFTAGInfo();
ReadUhfTagInfo ri = i.toReadUhfTagInfo();

At this moment my toReadUhfTagInfo function is at top level, but finally I want to put it in my ReadUhfTagInfo class, like this:

class ReadUhfTagInfo(var epc: String, var cnt: Int, var rssi: Int?)
{
    fun UHFTAGInfo.toReadUhfTagInfo(): ReadUhfTagInfo {
        return ReadUhfTagInfo(this.epc, this.count, this.rssi.toIntOrNull())
    }
}

Answer 1

You can call Kotlin extension functions from Java, sure, but you can't call them with extension function syntax, you must call them like static methods. If you, for example, define

// file: Foo.kt

fun Bar.baz() { ... }

then in Java, you would call this as

FooKt.baz(bar);