MultiThreading Data Select

package org.apache.tomcat.jdbc.pool.jmx;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

import org.springframework.orm.ibatis.support.SqlMapClientDaoSupport;

public class MockCommonDao extends SqlMapClientDaoSupport {

ArrayList<ArrayList> listOlists = new ArrayList<ArrayList>();

public List selectByExample(List<Object> example)
   {
List<Future<Object>> listOlists = null;
ExecutorService executor = Executors.newFixedThreadPool(example.size());
List<TransactionImpl> callingList = new ArrayList<MockCommonDao.TransactionImpl>();
for (int i = 0; i < example.size(); i++) {
             TransactionImpl localImpl = new TransactionImpl(example.get(i));
             callingList.add(localImpl);
         }
try {
           
listOlists = executor.invokeAll(callingList);

         } catch (InterruptedException e) {
           
         }
         return listOlists;
       

               
   
     
   }
private String getClassNameFromExample(Object example)
   {
       String tableName = example.getClass().getName();
       int cnt = tableName.indexOf("Example");
       int last = tableName.lastIndexOf('.');
       tableName = tableName.substring(last + 1, cnt);
       return tableName.toUpperCase();
   }
 private class TransactionImpl implements Callable<Object>{
 private Object example;


 TransactionImpl(Object Criteria) {
           this.example = Criteria;

       }


@Override
public Object call() throws Exception {

            List list = getSqlMapClientTemplate().queryForList((new StringBuilder(String.valueOf(getClassNameFromExample(example)))).append(".ibatorgenerated_selectByExample").toString(), example);
            listOlists.add((ArrayList) list);
            return listOlists;
 }
 }}