LiveData.getValue() returns null with Room

Question

Java POJO Object

public class Section {

    @ColumnInfo(name=\"section_id\")
    public int mSectionId;

    @ColumnInfo(name=\"section_name\")
    public S         


        

Answer 1

On the next line I am checking sections.getValue() which is always giving me null although I have data in the DataBase and later I am getting the value in the onChanged() method.

This is a normal behavior, because queries that return LiveData, are working asynchronous. The value is null that moment.

So calling this method

LiveData> getAllSections();

you will get the result later here

sections.observe(this, new Observer>() {
@Override
public void onChanged(@Nullable List
 sections){

}
});

from documentation:

Room does not allow accessing the database on the main thread unless you called allowMainThreadQueries() on the builder because it might potentially lock the UI for a long periods of time. Asynchronous queries (queries that return LiveData or RxJava Flowable) are exempt from this rule since they asynchronously run the query on a background thread when needed.