I am use abstract class:

abstract class Flower { public abstract String whatsYourName(); }

class Jasmine extends Flower {

@Override
public String whatsYourName() {
    return "Jasmine";
}

}

class Lily extends Flower {

@Override
public String whatsYourName() {
    return "Lily";
}

}

abstract class Region { public abstract Flower yourNationalFlower(); }

class WestBengal extends Region {

@Override
public Jasmine yourNationalFlower() {
    return new Jasmine();
}

}

class AndhraPradesh extends Region {

@Override
public Lily yourNationalFlower() {
    return new Lily();
}

}