Introduction Instead of callback function hell, we will use an elegant way `RxJava2` to achieve it. How to do We can use `subject` or `processor`(with backpressure) to omit a callback function. Otherwise, if we just use an `observable`, it cant invoke `onNext` somewhere. Due to an `observable` will create so many new objects, using them is bette…

Using RxJava2 in `callback`..kt

// A class
fun caller() {
    // here we will set callback function.
    callbackProcessor.subscriby {
        // Here I can get `5566`, and do somthing.
    }
}

// B class
fun callee() {
    val callbackProcessor = PublishProcessor.create<Int>()

    // This is callback place.
    fun onXXFun() {
        callbackProcessor.onNext(5566)
    }
}