error in the importing the database

Question

package com.Wblower.db;

import java.util.Hashtable; import java.util.Vector;

import org.garret.perst.Iterator; import org.garret.perst.Key;

public class ContactlistdatabaseQueries { public static Vector ContactDBVec = new Vector(); public static Hashtable ContactDBhash = new Hashtable();

public static void insertSingleContactlist(
        Contactlistdatabasetable Contactlist) {

    Root root = (Root) DataBaseConnectivity.db.getRoot();
    root.Contactlistdatabasetable.put(new Key(""), Contactlist);
    DataBaseConnectivity.db.commit();
}

public static void insertVectorContactlist(Vector ContactlistVector) {

    System.out.println("Root set");
    Root root = (Root) DataBaseConnectivity.db.getRoot();
    int length = ContactlistVector.size();
    for (int i = 0; i < length; i++) {

        Contactlistdatabasetable Contactlist = (Contactlistdatabasetable) ContactlistVector
                .elementAt(i);
        root.Contactlistdatabasetable.put(new Key(""), Contactlist);
        System.out.println(" insert single Contactlist ---  "
                + Contactlist.feedtype + ", " + Contactlist.event + ", "
                + Contactlist.firstname + "," + Contactlist.lastname + ","
                + Contactlist.email + "," + Contactlist.email1 + ","
                + Contactlist.mobile + "," + Contactlist.mobile1 + ","
                + Contactlist.mobile2 + "," + Contactlist.web + ","
                + Contactlist.company + "," + Contactlist.address + ","
                + Contactlist.address1 + "," + Contactlist.timestamp);
    }

    // DataBaseConnectivity.db.commit();
}

public static void selectPrefixContactlist(String selectStr) {
    Root root = (Root) DataBaseConnectivity.db.getRoot();
    System.out.println("root created");
    Iterator itr3 = root.Contactlistdatabasetable.prefixIterator(selectStr);
    clearContactlist();
    while (itr3.hasNext()) {
        System.out
                .println("----In  select prefix Header data iterator----");
        Contactlistdatabasetable Contactlist = (Contactlistdatabasetable) itr3
                .next();

    }

}

public static void selectWholeContactlist() {
    Root root = (Root) DataBaseConnectivity.db.getRoot();
    System.out.println("root created");

    ContactDBhash.clear();
    Iterator itr3 = root.Contactlistdatabasetable.iterator();
    System.out.println("In  itr3---------" + itr3);
    System.out.println("In  itr3 1111111---------" + itr3.hasNext());
    clearContactlist();
    int i = 0;
    while (itr3.hasNext()) {
        System.out
                .println("@@@@@ in select whole Header data itr while loop @@@@@");
        Contactlistdatabasetable Contactlist = (Contactlistdatabasetable) itr3
                .next();
        System.out.println(" insert single contact ---  "
                + Contactlist.feedtype + ", " + Contactlist.event + ", "
                + Contactlist.firstname + "," + Contactlist.lastname + ","
                + Contactlist.email + "," + Contactlist.email1 + ","
                + Contactlist.mobile + "," + Contactlist.mobile1 + ","
                + Contactlist.mobile2 + "," + Contactlist.web + ","
                + Contactlist.company + "," + Contactlist.address + ","
                + Contactlist.address1 + "," + Contactlist.timestamp);
        i++;
    }
    System.out.println("Number of rows in Contactlist==" + i);

}

public static void removePrefixContactlistDetails(
        Contactlistdatabasetable Contactlist, String selectStr) {
    Root root = (Root) DataBaseConnectivity.db.getRoot();
    System.out.println("root created");
    root.Contactlistdatabasetable.remove(new Key("", Contactlist));
    System.out.println(" insert single Header data ---  "
            + Contactlist.feedtype + ", " + Contactlist.event + ", "
            + Contactlist.firstname + "," + Contactlist.lastname + ","
            + Contactlist.email + "," + Contactlist.email1 + ","
            + Contactlist.mobile + "," + Contactlist.mobile1 + ","
            + Contactlist.mobile2 + "," + Contactlist.web + ","
            + Contactlist.company + "," + Contactlist.address + ","
            + Contactlist.address1 + "," + Contactlist.timestamp);
    DataBaseConnectivity.db.commit();

}
public static void removeAllConatctlistDetails() 
{
    Root root = (Root) DataBaseConnectivity.db.getRoot();
    System.out.println("root created");
    root.Contactlistdatabasetable.clear();

    DataBaseConnectivity.db.commit();

}

public static void updatePrefixContactlistDetails(String key, Contactlistdatabasetable Contactlist) 
{

    Root root = (Root) DataBaseConnectivity.db.getRoot();
    root.Contactlistdatabasetable.set(new Key(key), Contactlist);
    DataBaseConnectivity.db.commit();

}

public static Vector getContactData() 
{
    return ContactDBVec;
}

private static void clearContactlist() {
    // TODO Auto-generated method stub

}

}

this is were i am able to fetch the data of a paticular class