Saving Data on Android

Kotlin Coroutines
 or creating your own 
threads.
Next, change the 
deleteQuestions()
 to the following code:
override
 fun deleteQuestions() { 
  
AsyncTask
.execute { quizDao.clearQuestions() } 
}
Just like 
saveAnswer()
 and 
saveQuestion()
, this method uses an 
AsyncTask
 to 
execute one of your DAO's methods: 
clearQuestions()
. As the name implies, 
deleteQuestions()
 will delete all the questions in your database.
Finally, implement the remainder of the code like this:
override
 
fun
 
getSavedQuestions
()
 = allQuestions 
 
override
 
fun
 
getQuestionAndAllAnswers
()
 = 
allQuestionsAndAllAnswers
Once again, because you're using 
LiveData
, if you ever need to access fresh 
information from the database, you simply have to observe the preloaded 
LiveData
s 
in your repository. And that is all you need to create a repository that interacts with 
your database using your Data Access Objects.
Saving Data on Android Chapter 9: Using Room with Google's Architecture Components
raywenderlich.com
154

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At this point, you might be wondering: 
Why do I need to define a repository that 
interacts with my DAOs? Can't I simply use my DAOs inside my ViewModels?
Well, you certainly can use your DAOs directly inside your 
ViewModel
s, but you also 
need to remember a very important principle in programming: