The correct way to convert this code to Kotlin is what Jesper posted above. Both his code and your code (which is also correct but more verbose than necessary) allow you to use values outside of the constructor.
By declaring context and arrayList as we’ve shown you, they are available in methods in your class. Is there something specific that you are having trouble with and that give you an error? If yes, then please show your code and explain what error message you get, then we can tell what’s wrong with it and how to fix it.
Note here that there is no constructor body as such (only field initialisers). The block in curly braces is the class body, not the constructor body. As such val arrayList and val context are property declarations with implicit backing fields. The android convention of fields prefixed with m doesn’t work with Kotlin properties.