Troubleshooting guide

3: Storing data

Code sample: Saving user name and password information

This code sample demonstrates how to create an application for BlackBerry® device users that lets them view

their current user names and passwords, type new user names and passwords, and save changes.

Example: UserInfo.java

/**

* UserInfo.java

package com.rim.samples.docs.userinfo;

import net.rim.device.api.ui.*;

import net.rim.device.api.ui.component.*;

import net.rim.device.api.ui.container.*;

import net.rim.device.api.system.*;

import net.rim.device.api.util.*;

import java.util.*;

import net.rim.device.api.i18n.*;

import com.rim.samples.docs.resource.*;

public class UserInfo extends UiApplication implements UserInfoResource

{

private static PersistentObject store;

private static ResourceBundle _resources;

private AutoTextEditField usernamefield;

private PasswordEditField passwordfield;

Retrieve persistent data. 1. Invoke getContents() on a PersistentObject.

2. To convert the object that PersistentObject.getContents() returns to a specific object type,

perform an explicit cast on the object that

PersistentObject.getContents() returns.

synchronized(store) {

String[] currentinfo = (String[])store.getContents();

if(currentinfo == null) {

Dialog.alert(_resources.getString(APP_ERROR));

}

else {

currentusernamefield.setText(currentinfo[0]);

currentpasswordfield.setText(currentinfo[1]);

}}

Delete all persistent data

from an application.

If you delete the .cod file that defines a PersistentStore, then all persistent objects that the .cod file

created are deleted.

>Invoke PersistentStore.destroyPersistentObject(), providing as a parameter a unique key

for the

PersistentObject.

Delete specific persistent

data from an application.

> To delete individual data, treat the data as normal object, and delete references to it. A garbage collected

operation delete the data.

Task Steps