java3.java

java3.java

public class OrderQuery {
    public static FilterableCollection of(Field1 field) {
        return new FilterableByQueryField1(field);
    }

    public static FilterableCollection of(Field2 field) {
        return new FilterableByQueryField2(field);
    }

    public static FilterableCollection of(Field3 field) {
        return new FilterableByQueryField3(field);
    }


    public interface FilterableByQuery<T> {
        Collection<T> filterBy(Field1 field1);
        Collection<T> filterBy(Field2 field2);
        Collection<T> filterBy(Field3 field3);
        Collection<T> filterByQuery(FilterableCollection query);
    }

    public interface FilterableCollection {
        public <T> Collection<T> filterBy(FilterableByQuery<T> filter);
    }

    private static class FilterableByQueryField1 implements FilterableCollection {
        private final Field1 field;

        private FilterableByQueryField1(Field1 field) {
            this.field = field;
        }

        @Override
        public <T> Collection<T> filterBy(FilterableByQuery<T> filter) {
            return filter.filterBy(field);
        }
    }

    private static class FilterableByQueryField2 implements FilterableCollection {
        private final Field2 field;

        private FilterableByQueryField2(Field2 field) {
            this.field = field;
        }

        @Override
        public <T> Collection<T> filterBy(FilterableByQuery<T> filter) {
            return filter.filterBy(field);
        }
    }

    private static class FilterableByQueryField3 implements FilterableCollection {
        private final Field3 field;

        private FilterableByQueryField3(Field3 field) {
            this.field = field;
        }

        @Override
        public <T> Collection<T> filterBy(FilterableByQuery<T> filter) {
            return filter.filterBy(field);
        }
    }
}

// repository
public class OrderRepository implements OrderQuery.FilterableByQuery<Order> {
    @Override
    public Collection<Order> filterBy(Field1 field1) {
        throw new RuntimeException("Not implemented");
    }

    @Override
    public Collection<Order> filterBy(Field2 field2) {
        throw new RuntimeException("Not implemented");
    }

    @Override
    public Collection<Order> filterBy(Field3 field3) {
        throw new RuntimeException("Not implemented");
    }

    @Override
    public Collection<Order> filterByQuery(OrderQuery.FilterableCollection query) {
        return query.filterBy(this);
    }
}

// usage
OrderQuery.FilterableCollection query = OrderQuery.of(new Field1("asdf"));
Collection<Order> orders = this.repository.filterByQuery(query);