Implement reading of contact from phone book Using Hashtable in J2ME

Question

I ran into a bind whereby I had to sort the data read from the phones PIM. In doing this I lost the other to which each contact field was referenced to the telephone number because I made use of 2 separate vectors as illustrated below
Before sorting

 Nna - +445535533                       
Ex - +373773737                         
Ab - +234575757                         
After sorting.(Which shouldn't be)
 Ab - +445535533
 Ex - +373773737
 Nna  - +234575757

This gives an undesired behavior since the sort removes the index to index pointer of the vectors and a selected name (in a Multiple list Box) will get a wrong number.
Alternatively,
I used a hashtable, with the intention of using the names as keys and numbers as the values.
But this pairing means duplicate names being used as keys will not be allowed. Thus I made it a i.e the phone number as keys instead. I don't want to sound like a cry baby so I stop here for a while and so you the code with a hope u guys would understand it

MY QUESTION
1. Is there a better way/algorithm to implement this?
2. How do I implement the getSelectedItems() in such a ways that it grabs the numbers of the selected indexes of a MULTIPLE CHOICE LIST from a hashTable

import java.util.Enumeration;
import java.util.Vector;
import java.util.Hashtable;
import javax.microedition.lcdui.List;
import javax.microedition.pim.Contact;
import javax.microedition.pim.ContactList;
import javax.microedition.pim.PIM;
import javax.microedition.pim.PIMException;

/**
 *
 * @author nnanna
 */
public class LoadContacts implements Operation {

    private boolean available;
    private Vector telNames = new Vector();
    Vector telNumbers = new Vector();
    Hashtable Listcontact = new Hashtable();
    private String[] names;

    public Vector getTelNames() {
        return telNames;
    }

    public Hashtable getListcontact() {
        return Listcontact;
    }

    public void execute() {
        try {
// go through all the lists
            String[] allContactLists = PIM.getInstance().listPIMLists(PIM.CONTACT_LIST);

            if (allContactLists.length != 0) {
                for (int i = 0; i < allContactLists.length; i++) {
                    System.out.println(allContactLists[i]);
                    System.out.println(allContactLists.length);
                    loadNames(allContactLists[i]);
                    System.out.println("Execute()");
                }

            } else {
                available = false;
            }
        } catch (PIMException e) {
            available = false;

        } catch (SecurityException e) {
            available = false;

        }
    }

    private void loadNames(String name) throws PIMException, SecurityException {
        ContactList contactList = null;

        try {
            contactList = (ContactList) PIM.getInstance().openPIMList(PIM.CONTACT_LIST, PIM.READ_ONLY, name);
            // First check that the fields we are interested in are supported(MODULARIZE)
            if (contactList.isSupportedField(Contact.FORMATTED_NAME) && contactList.isSupportedField(Contact.TEL)) {
                Enumeration items = contactList.items();
                Hashtable temp = new Hashtable();
                while (items.hasMoreElements()) {
                    Contact contact = (Contact) items.nextElement();
                    int telCount = contact.countValues(Contact.TEL);
                    int nameCount = contact.countValues(Contact.FORMATTED_NAME);
                    if (telCount > 0 && nameCount > 0) {
                        String contactName = contact.getString(Contact.FORMATTED_NAME, 0);
                        // go through all the phone availableContacts

                        for (int i = 0; i < telCount; i++) {
                            System.out.println("Read Telno");
                            int telAttributes = contact.getAttributes(Contact.TEL, i);
                            String telNumber = contact.getString(Contact.TEL, i);
                            Listcontact.put(telNumber, contactName);
                            temp.put(contactName, telNumber);
                        }
                        names = getSortedList();
//                            Listcontact = temp;
                        System.out.println(temp + "-------");
                        System.out.println(Listcontact + "*******");
                        shortenName(contactName, 20);
                    }
                    available = true;
                }
            } else {
                available = false;
            }
        } finally {
// always close it
            if (contactList != null) {
                contactList.close();
            }
        }
    }

    private void shortenName(String name, int length) {
        if (name.length() > length) {
            name = name.substring(0, 17) + "...";
        }
    }

    public Vector getSelectedItems(List lbx) {
        boolean[] arrSel = new boolean[lbx.size()];
        Vector selectedNumbers = new Vector();
        int selected = lbx.getSelectedFlags(arrSel);
        String selectedString;
        String result = "";
        for (int i = 0; i < arrSel.length; i++) {
            if (arrSel[i]) {
                selectedString = lbx.getString(lbx.getSelectedFlags(arrSel));
                result = result + " " + i;
                System.out.println(Listcontact.get(selectedString));
//                System.out.println(telNumbers.elementAt(i));
            }
        }
        return selectedNumbers;
    }

    private String[] sortResults(String data[]) {
        RecordSorter sorter = new RecordSorter();
        boolean changed = true;
        while (changed) {
            changed = false;
            for (int j = 0; j < (data.length - 1); j++) {
                String a = data[j], b = data[j + 1];
                if (a != null && b != null) {
                    int order = sorter.compare(a.getBytes(), b.getBytes());
                    if (order == RecordSorter.FOLLOWS) {
                        changed = true;
                        data[j] = b;
                        data[j + 1] = a;
                    }
                }
            }
        }
        return data;
    }

    public String[] getNames() {
        return names;
    }
        Vector elements = new Vector();
    private String[] getValueArray(Hashtable value) {

        System.out.println(Listcontact + " c");
        Enumeration e = value.elements();
        while (e.hasMoreElements()) {
            elements.addElement(e.nextElement());
        }
        String[] elementsArray = new String[elements.size()];
        elements.copyInto(elementsArray);
        elements.removeAllElements();
        System.out.println(elementsArray + " k");
        return elementsArray;
    }

    public void getDuplicates(Vector realValue) {
        Vector duplicate = new Vector();
        Enumeration e = realValue.elements();
        for (int i = 0; e.hasMoreElements(); i++) {
            if (duplicate.isEmpty() || !duplicate.elementAt(i).equals(e.nextElement())) {
                break;
            } else {
                duplicate.addElement(e.nextElement());
            }
        }
    }

    public String[] getSortedList() {
        return sortResults(getValueArray(Listcontact));
    }
}

Answer 1

Let me reiterate you requirement: You want a method that will sort the contacts read from native phonebook, then alphabetically sort them on name.

Following is the approach,

Replace the vectors and hash-tables in your code with a single vector, say contactListVector, containing elements of type ContactItem, don't worry this class is explained below. Fundamentally the contact's name and number(s) are linked together in a ContactItem, hence you do not have to worry about there mappings which reduces the usage of redundant data structures.

class ContactItem {
    private String name;
    private String tnumber;  //this can also be a data structure 
                             //for storing multiple numbers

    ContactItem( String name, String tnumber) {
        this.name = name;
        this.tnumber = tnumber;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getTnumber() {
        return tnumber;
    }

    public void setTnumber(String tnumber) {
        this.tnumber = tnumber;
    }        
}

You can reuse the sorting algorithm on contactListVector by comparing the member variable ContactItem.name of the vector element. Also you can deploy different sorts on member variables numbers and/or names. Also there are lots of libraries for JavaME available that have better sorting algorithm's implemented if need be use them.

I would recommend you to perform the sorting once on the contactListVector elements at the end of your method loadNames(...) maybe in the finally block triggered by some boolean variable. The current sorting call in each iteration on items enumeration is expensive and time consuming.

Also you can serialize / deserialize the ContactItem thus persist your contact list.

Let me know if you need detailed explanation.

Answer 2

I would suggest you to have Contact class with name and Vector of numbers. And instead of sorting names array sort the array of contacts.

Answer 3

What about inserting the contact name and numbers inside a recordStore , so you can later make a sort by creating a class which implements RecordComparator.

Answer 4

This statement in your code makes no sense:

selectedString = lbx.getString(lbx.getSelectedFlags(arrSel))

Per lcdui List API documentation above will return the string located at the index equal to the number of selected elements why would you need that?

---

If you need to output selected text for debugging purposes, use lbx.getString(i) instead.

To implement the getSelectedItems() in such a ways that it grabs the numbers of the selected indexes of a MULTIPLE CHOICE LIST do about as follows:

    public Vector getSelectedItems(List lbx) {
        boolean[] arrSel = new boolean[lbx.size()];
        Vector selectedNumbers = new Vector();
        int selected = lbx.getSelectedFlags(arrSel);
        System.out.println("selected: [" + selected + "] elements in list");
        String selectedString;
        String result = "";
        for (int i = 0; i < arrSel.length; i++) {
            if (arrSel[i]) {
                // here, i is the selected index
                selectedNumbers.addElement(new Integer(i)); // add i to result
                String selectedString = lbx.getString(i);
                System.out.println("selected [" + selectedString
                        + "] text at index: [" + i + "]");
            }
        }
        return selectedNumbers;
    }

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As for sorting needs, just drop the HashTable and use Vector of properly designed objects instead as suggested in another answer - with your own sorting algorithm or one from some 3rd party J2ME library.