How use kotlin-observable at pure java !!?

[CMingTseng]

Dear Sir

i want create general library -- use at java & kotlin final at Android !!

at Android i have google databinding library --- ObservableList/ObservableArrayList

https://developer.android.google.cn/reference/android/databinding/ObservableArrayList?hl=zh-cn

but it maybe not full support ( aar file ??!! )

at java i have ObservableList

now want use kotlin

i create a ObservableListWrapper

like this

val all_hours = ObservableListWrapper( ArrayList())

i can use

all_hours.onAdd += { anchor, index -> println("Show glob all_hours add $anchor __at $index") }

let me get all_hours notify change -- add

but at Java

onAdd --> getOnAdd()

but += ? <---- how to replace ?

THX