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alz-ahm/mvvm-send-event-with-wrapper-class.kt

Last active August 27, 2019 15:26
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mvvm-send-event-with-wrapper-class.kt
open class Event<out T>(private val content: T) {
var hasBeenHandled = false
private set // Allow external read but not write
/**
* Returns the content and prevents its use again.
*/
fun getContentIfNotHandledOrReturnNull(): T? {
return if (hasBeenHandled) {
null
} else {
hasBeenHandled = true
content
}
}
/**
* Returns the content, even if it's already been handled.
*/
fun peekContent(): T = content
}
class MyViewModel() : ViewModel(){
val networkError = MutableLiveData<Event<String>>()
}
viewModel.networkError.observe(this, Observer { event ->
event?.getContentIfNotHandledOrReturnNull()?.let {
showToast(it)
}
})
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