How to shorten a conditional expression with Android Databinding - android-layout

Question

I just want to make the following snippet shorter and more readable.
<LinearLayout android:visibility="#{ viewModel.prediction.intent == PredictionIntentType.MEETING_FOLLOWUP || (viewModel.prediction.intent == PredictionIntentType.FOLLOWUP && !viewModel.isMeetingViewGroupShown) || (viewModel.prediction.intent == PredictionIntentType.MEETING && viewModel.isMeetingViewGroupShown) ? View.VISIBLE : View.GONE }" />
When I do it multiline (see below) it won't compile
<LinearLayout
android:visibility="#{ viewModel.prediction.intent == PredictionIntentType.MEETING_FOLLOWUP
|| (viewModel.prediction.intent == PredictionIntentType.FOLLOWUP && !viewModel.isMeetingViewGroupShown)
|| (viewModel.prediction.intent == PredictionIntentType.MEETING && viewModel.isMeetingViewGroupShown)
? View.VISIBLE : View.GONE }" />
Ultimately, I just want it to look something like:
<LinearLayout android:visibility="#{ viewModel.someViewVisibility }" />
I'm using Java and viewModel.prediction is of type LiveData<Prediction> and viewmodel.isMeetingViewGroupShown is of type LiveData<Boolean> if that helps.

Answer 1

You should have all your logic in code files not in xml. So what you need is a boolean in your code file that looks something like this.
val visible = prediction.intent == PredictionIntentType.MEETING_FOLLOWUP
|| (prediction.intent == PredictionIntentType.FOLLOWUP && !isMeetingViewGroupShown)
|| (prediction.intent == PredictionIntentType.MEETING && isMeetingViewGroupShown
In your code file also add this method.
#BindingAdapter("visible")
fun bindVisible(linearLayout: LinearLayout, visible: Boolean) {
if(visible){
linearLayout.setVisibility(View.VISIBLE);
}else{
linearLayout.setVisibility(View.GONE);
}
}
In your xml add this to your linear layout
app:visible="#{viewModel.visible}

Answer 2

Ultimately, I just want it to look something like:
<LinearLayout android:visibility="#{ viewModel.someViewVisibility }" />
So do exactly that:
ViewModel:
val someViewVisibility: Int
#Bindable get() {
return if (prediction.intent == PredictionIntentType.MEETING_FOLLOWUP || (prediction.intent == PredictionIntentType.FOLLOWUP && !isMeetingViewGroupShown) || (prediction.intent == PredictionIntentType.MEETING && isMeetingViewGroupShown)) View.VISIBLE else View.GONE
}
With the property defined in your viewmodel, your simplified logic will work. Plus, now you can write a unit test for someViewVisibility and prove it works. :)
Hope that helps!