Is it possible to make one LiveData of two LiveDatas?

Question

I have two DAOs, two Repositories and two POJOs. There is some way to create one Livedata of two? I need it to make single list for Recyclerview. POJOs are similar objects.<

Answer 1

Instead of having a class to add 2 live datas, another class to add 3 live datas, etc. We can use a more abstract way where we can add as many live datas as we want.

import androidx.lifecycle.LiveData
import androidx.lifecycle.MediatorLiveData

/**
 * CombinedLiveData is a helper class to combine results from multiple LiveData sources.
 * @param liveDatas Variable number of LiveData arguments.
 * @param combine   Function reference that will be used to combine all LiveData data.
 * @param R         The type of data returned after combining all LiveData data.
 * Usage:
 * CombinedLiveData(
 *     getLiveData1(),
 *     getLiveData2(),
 *     ... ,
 *     getLiveDataN()
 * ) { datas: List ->
 *     // Use datas[0], datas[1], ..., datas[N] to return a SomeType value
 * }
 */
class CombinedLiveData(vararg liveDatas: LiveData<*>,
                          private val combine: (datas: List) -> R) : MediatorLiveData() {

    private val datas: MutableList = MutableList(liveDatas.size) { null }

    init {
        for(i in liveDatas.indices){
            super.addSource(liveDatas[i]) {
                datas[i] = it
                value = combine(datas)
            }
        }
    }
}