live-data-mutable.kt

class MyViewModel : BaseViewModel() {
    val data: LiveData<String> = MutableLiveData()

    fun load() {
        data.value = "Hello, World"
    }
}

class MyActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        val vm = ViewModelProviders.of(this).get(MyViewModel::class.java)

        vm.data.observe(this, Observer {
            Toast.makeText(this, it, Toast.LENGTH_SHORT).show()
        })
    }
}