Build error with Realm

Error:A default public constructor with no argument must be declared

You can add the desired default constructor to the specified class and check back.

Change

DataBaseQuestion() {
}

to

public DataBaseQuestion() {
}

you forgot public modifier.

Your program probably tries to reach it outside of package context, which means that it looks only for public constructors. It finds one - the one which requires constructor-args, but doesn't see package private one. Adding "public" access modifier should solve the problem.

public DataBaseQuestion(){}

Note: You should look at lombok in your spare time, so that you do not manually handle creation of getters, setters, AllArgsContsructors or NoArgsConstructors