[Solved] Algorithm for quantity selection [closed]

You should have a Product class. Each product object has different quantity measures and increment methods. Something like this:

public abstract class Product {
    String quantityMeasure; //You can encapsulate this with a getter
    public abstract int step (int value); //here you want to increment "value" with different algorithms.
}

Now you can create different product subclasses like this:

public class FruitProduct extends Product {
    public abstract int step (int value) {
        //implementation here
    }

    public FruitProduct () {
        quantityMeasure = "grams";
    }
}

Now you can get the quantity measure using the Product objects.

EDIT:

You can also make the Product type an interface like this:

public interface Product {
    int step(int value);
    String getQuantityMeasure();
}

Remember to implement the getQuantityMeasure method as well!

public String getQuantityMeasure() {
    return "grams";
}