EDIT

package eu.etaxonomy.cdm.api.service;

import java.util.ArrayList;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Service;

import org.springframework.transaction.annotation.Transactional;

import eu.etaxonomy.cdm.api.service.pager.Pager;

import eu.etaxonomy.cdm.api.service.pager.PagerUtils;

import eu.etaxonomy.cdm.api.service.pager.impl.AbstractPagerImpl;

import eu.etaxonomy.cdm.api.service.pager.impl.DefaultPagerImpl;

import eu.etaxonomy.cdm.model.description.IIdentificationKey;

import eu.etaxonomy.cdm.model.taxon.TaxonBase;

import eu.etaxonomy.cdm.persistence.dao.description.IIdentificationKeyDao;

@Service

@Transactional(readOnly = true)

public class IdentificationKeyServiceImpl implements IIdentificationKeyService {

    IIdentificationKeyDao dao;

    @Autowired

    public void setDao(IIdentificationKeyDao dao) {

        this.dao = dao;

    }

    @Override

    public Pager<IIdentificationKey> page(Integer pageSize, Integer pageNumber,	List<String> propertyPaths) {

        long numberOfResults = dao.count();

        List<IIdentificationKey> results = new ArrayList<>();

        if(numberOfResults > 0) { // no point checking again //TODO use AbstractPagerImpl.hasResultsInRange(numberOfResults, pageNumber, pageSize)

            Integer limit = PagerUtils.limitFor(pageSize);

            Integer start = PagerUtils.startFor(pageSize, pageNumber);

            results = dao.list(limit, start, propertyPaths);

        }

        return new DefaultPagerImpl<>(pageNumber, numberOfResults, pageSize, results);

    }

    @Override

    public <T extends IIdentificationKey> Pager<T> findKeysConvering(TaxonBase taxon,

            Class<T> type, Integer pageSize,

            Integer pageNumber, List<String> propertyPaths) {

        Long numberOfResults = dao.countByTaxonomicScope(taxon.getUuid(), type);

        List<T> results = new ArrayList<T>();

        if(AbstractPagerImpl.hasResultsInRange(numberOfResults, pageNumber, pageSize)){

            results = dao.findByTaxonomicScope(taxon.getUuid(), type, pageSize, pageNumber, propertyPaths);

        }

        return new DefaultPagerImpl<T>(pageNumber, numberOfResults, pageSize, results);

    }

}