android, observer two different mutable live data at once

Question

I want to observe two different mutable live data at once. is there any way I can achieve this in android, both data are lies with different ViewModel also.

Answer 1

You can use MediatorLiveData to combine two live data sources into one. Here's a quick example that combines livedata1 and livedata2 from two separate view models into a MediatorLiveData, which emits a data class that contains the result from livedata1 and livedata2. Anytime livedata1 or livedata2 changes, the mediator will be triggered

data class CombinedResult(val firstData: DataType1, val secondData: DataType2)

private fun createLiveDataMediator() : LiveData<CombinedResult> {

    val result = MediatorLiveData<CombinedResult>()

    val firstLiveData = myViewModel.getLiveData1()
    val secondLiveData = mySecondViewModel.getLiveData2()

    result.addSource(firstLiveData) {
        result.value = CombinedResult(firstLiveData.value, secondLiveData.value)
    }
    result.addSource(secondLiveData) {
        result.value = CombinedResult(firstLiveData.value, secondLiveData.value)
    }

    return result
}