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Exploring J2ME: Building an expense detail form the detail form used to edit an existing expense item or add a new one and let you get your feet wet with the Item family of components.

Exploring J2ME: Using the Record Management System creating a record store for the ExpensesApp MIDlet suite using the MIDP’s Record Management System (RMS).

Exploring J2ME: Sorting records the RMS’s record-sorting API, the RecordEnumeration class and RecordComparator interface, both of which you find in the javax.microedition.rms package.

Exploring J2ME: Being a good mobile citizen polish up ExpensesApp a bit by reducing its memory requirements and correcting some data problems using the record change notification API.

J2ME for the Java Developer How does Sun's Java 2 Micro Edition (J2ME) platform for smaller devices compare to the more familiar Java 2 Standard Edition? Let's dig into the details a little...

Deploy Your J2ME Application on a Sprint Phone Web server configuration and caching problems are just two of the obstacles you'll need to overcome when you deploy Java applications on cell phones. This article provides the workarounds and solutions you'll need to overcome these bumps.

Programming Strategies for Small Devices (PDF) If in Doubt, Do Not Use Java, Move Computation to the Server, Simplify the Application, Build Smaller Applications, Remove the Public Members, Use Less Memory at Run Time, Use Scalar Types, Do Not Depend on the Garbage Collector, Help the Garbage Collector, Use Lazy Instantiation, Release Resources Early, Reuse Objects, Avoid Exceptions, Code with Performance in Mind, Use Local Variables, Avoid String Concatenation, Use Threads, but Avoid Synchronization, Separate the Model...

Java 2 Micro Edition (J2ME) Specifications (PDF) Introducing the Micro Edition, A New Virtual Machine, New and Changed Classes, Configurations and Profiles, Building Blocks, The KVM, Related Technologies,

Developing Custom Components for the Mobile Information Device Profile A question that novice MIDP programmers often ask is "How can I extend the MIDP user interface classes to define my own custom components?" You might want to extend the TextField class, for example, to support more kinds of constraints or alternate forms of input. Or you might want to define a completely new kind of UI component...

Using Passwords to Protect Your MIDlets Security is always a concern when you are writing an application that deals with sensitive data. It's especially so on handheld devices, which are more apt to be lost or stolen than a desktop computer. A handheld device is likely to hold truly personal information that you don't want strangers to know, things such as important phone numbers and addresses. Safeguarding that information should always be a priority...

Adapting Images for MIDP Devices The MIDP supports the display of bitmapped images, but not with the flexibility of J2SE. The MIDP specification only requires support for a single format, the PNG format. PNG was developed primarily as a replacement for the older GIF, and has the support of the World Wide Web consortium. Modern web browsers and image editors can load and save images in PNG format..

Making HTTP Connections Using Background Threads All user interface frameworks share some basic concepts. This is true no matter if the UI framework is the LCDUI classes defined by the MIDP, or the AWT and Swing classes defined by J2SE. One of the basic concepts is that the user interface must always be responsive to the user's interaction...

Using MIDP Gauges The MIDP defines a number of high-level user interface components. Most of these components are designed to be placed on a top-level window called a form. Such components are referred to as items, because they all extend the javax.microedition.lcdui.Item class. The form itself is an instance of the javax.microedition.lcdui.Form class, and acts primarily as a container for items...

Building Splash Screens for MIDlets A splash screen is an informational screen that presents the name and version of an application, along with any necessary legal information such as the copyright and trademark notices. It's something you might want your MIDlets to display on startup. Adding a splash screen to a MIDlet is easy to do, but there are a few things to watch out for...

Client-Server Communication over HTTP using MIDP and Servlets Many, if not most, MIDP applications have a server-side piece to them. In other words, a client-server paradigm is used to offload complicated work from the limited capabilities of the MIDP device to the more capable server environment. Because the MIDP 1.0 specification only mandates support for HTTP, all client-server communication must be done through an HTTP gateway...

Drawing Flicker-Free Graphics with the MIDP The term "double buffering" refers to a common technique used in computer graphics. If you consider a device's display to be a memory buffer into which drawing primitives write (the drawing primitives are the basic drawing methods such as drawLine and drawArc), with double buffering you draw into a second, offscreen memory buffer and then copy the entire contents of the second buffer into the display buffer...

Parsing XML in CLDC-based Profiles XML is a portable, text-based way of representing structured data. More and more applications are using XML to exchange information, and at some point your CLDC-based applications are going to need to process XML documents. Over time, even HTML pages will likely migrate to an XML-based format called XHTML...

Using the MIDP List Component The MIDP groups its user interface components into two sets of classes: the high-level API and the low-level API. With the high-level API you define your user interface using a set of platform-independent abstractions and let the MIDP implementation decide the look and behavior of the user interface...

Enumerating, Filtering, and Sorting MIDP Record Stores The RMS, part of the MIDP, lets you store arbitrary byte arrays as records in a database. The set of records is referred to as a record store. The RMS assigns a record ID to each record when it is created. The record ID is an integer greater than or equal to 1. The application uses this ID to get and set the content of a record...

The Connected Device Configuration and the Foundation Profile Much of what's been written about J2ME talks about the Connected Limited Device Configuration. The CLDC defines an extremely small subset of the Java Platform for very limited devices -- devices, like cellular telephones, that do not have enough memory or enough processing power to handle a full-blown Java implementation. There is, however, another configuration available that is midway between the CLDC and a full J2SE implementation: the Connected Device Profile...

Handling Multiple Simultaneous MIDP Alerts If you write a multithreaded MIDP application it's easy to trigger two or more alerts simultaneously. In other words, while one alert is being displayed, a second alert is triggered. Dealing with this situation is not as simple as you might think. Alerts are displayed using the two-argument form of the Display object's setCurrent method...

Using Timers One of the improvements in version 1.3 of J2SE are classes that make it simpler to schedule tasks for execution by a background thread. The MIDP also includes these new classes, so J2ME developers also benefit...

An Introduction to the High-Level User Interface API: Alerts and Tickers The MIDP includes both a low-level UI API and a high-level UI API. The low-level API gives you complete access to a device's screen and to raw key and pointer events. However, no user interface controls are available with the low-level API -- your application must explicitly draw buttons and other familiar controls. This is the price you pay for the flexibility of the low-level API...

Using Record Stores Efficiently The data in a record store is stored in chunks called records. A record is a set of arbitrary binary data, basically an array of bytes. You always read or write an entire record at once, using the getRecord, addRecord and setRecord methods of the RecordStore class...

Using the MIDP Low-Level User Interface API With J2ME, profiles are responsible for defining the user interface (UI) API. The MIDP defines two such APIs, referred to as the high-level and low-level APIs. The high-level API requires you to use task-oriented abstractions to define what the user interface does. You have no real control over what gets drawn on the screen -- the implementation selects the best approach for the device...

Making Connections With the CLDC As you can tell from its name, the Connected Limited Device Configuration (CLDC) is designed for connected devices. A connected device has the ability to connect to the outside world, whether the connection is serial, infrared, wireless, or something else entirely. How then do you take advantage of this connectivity in your Java applications? The answer is: through a set of classes called the Generic Connection framework, or GCF for short.

Record Management System Basics The Mobile Information Device Profile (MIDP) defines a set of classes for storing and retrieving data. These classes are called the Record Management System (RMS). With the RMS, it's possible to make data persist across invocations of a MIDlet. Different MIDlets in the same MIDlet suite can also use the RMS to share data...

Writing World-Aware J2ME Applications Well-written applications are both internationalized and localized. An application is internationalized, if it can correctly handle different encodings of character data. An application is localized, if it formats and interprets data (dates, times, timezones, currencies, messages and so on) according to rules specific to the user's locale. An application that is both internationalized and localized, can be referred to as "world-aware."...

Dealing With Missing J2SE Classes A problem you might run into when writing J2ME applications is how to deal with missing classes, that is, classes that are available in J2SE but not in J2ME. Note that J2ME configurations and profiles include subsets of the J2SE core classes. This means that specific methods or classes that you would normally use when writing a J2SE application are not always available. Ideally, you want to maximize the amount of code that is portable between your J2ME and J2SE applications...

The J2ME Development Cycle J2ME is a set of technologies and specifications that enable Java applications to run on devices such as cell phones, Personal Digital Assistants, or set top boxes, that are unable to accommodate the J2SE runtime environment. These devices have severe resource constraints when compared to desktop or server computers, limitations that kept the Java Platform off these devices until now...

Making HTTP Connections with MIDP HTTP connectivity is one of the requirements of the MIDP. A MIDP-enabled device must be able to interact with a web server through conventional HTTP requests. If the network doesn't directly support HTTP, then the device must route its requests through a gateway. But this is all transparent to the application developer...

JSR 82 Java APIs for Bluetooth Bluetooth is an important emerging standard for wireless integration of small devices. The specification will standardize a set of Java APIs to allow these Java-enabled devices to integrate into a Bluetooth environment.

J2ME Connected Device Configuration The J2ME Connected Device Configuration (CDC) provides the basis of the Java 2 platform, Micro Edition for devices that have a sufficient 32-bit microprocessor and ample memory.

Mobile Information Device Profile for the J2ME Platform This specification will define a profile that will extend and enhance the "J2ME Connected, Limited Device Configuration" (JSR-000030), enabling application development for mobile information appliances and voice communication devices.

J2ME Foundation Profile The J2ME Foundation Profile is a set of APIs meant for applications running on small devices that have some type of network connection.

Personal Profile Specification The J2ME Personal Profile provides the J2ME environment for those devices with a need for a high degree of Internet connectivity and web fidelity.

J2ME RMI Profile The J2ME RMI Profile provides Java platform to Java platform remote method invocation for Java devices and interoperates with J2SE RMI.

PDA Profile for the J2ME Platform This profile will provide user interface and data storage APIs for small, resource-limited handheld devices. It is based on the Connected, Limited Device Configuration (CLDC).

Mobile Information Device Next Generation This specification will define a profile that will extend and enhance the "J2ME Mobile Information Device Profile" (JSR-000037).

Wireless Telephony Communication APIs (WTCA) The purpose of this JSR is to define a set of optional APIs that provides standard access to wireless communication resources. This will allow 3rd party developers to build intelligent connected Java applications.

Connected Limited Device Configuration, Next Generation This specification will define a revised version of the J2METM Connected, Limited Device Configuration (CLDC).

Track wireless sessions with J2ME/MIDP (4/02) Every e-commerce application must support session tracking. Unfortunately, MIDP (Mobile Information Device Profile), a J2ME (Java 2 Platform, Micro Edition) technology, supports only the standard HTTP protocol, which is stateless. In this article, Michael Juntao Yuan and Ju Long explore ways to add session support into the current MIDP network API framework...

Micro Java Devices, Embedded Java, Java 2 Micro Edition (J2ME), KVM, Personal Java, Wireless Development

Event Handling Through the Item Object Event processing is essential to most every MIDlet. It's hard to imagine an application where there is no user interaction what-so-ever, even if this interaction is as simple as requesting to start or stop a MIDlet. In this article we'll learn the specifics of event handling using the MIDP Command object.

Nokia MIDP Example Applications Animated Example MIDlet, Networked MIDlet Example, Workflow Application Example, Game MIDlet Example Using The Nokia UI API, Nokia UI API Sound Example...

Developer Platforms: Guidelines For Testing J2ME Applications v1.0 This document lists fundamental issues that must be taken into account when testing J2ME™ MIDP applications.

Porting BREW Games to Java MIDP v1.0 This document assists developers who want to port BREW games to the J2ME platform, and who want to plan the development of BREW titles to make it easier to port them.

Your First Micro Java Game (12/02) Mobile phone manufacturers have embraced Java in a way that not even PC manufacturers have. Java is clearly one of the platforms of choice for mobile devices, and an ideal language for throwing together mobile games. The Mobile Information Device Profile (MIDP) of J2ME is a subset of the standard Java you know and love, with a few minor modifications. Writing a basic MIDlet game is simple as apple pie. This article will show you how to start cookin'.

J2ME Low-Level Network Programming with MIDP 2.0 (4/03) Version 1.0 of the Mobile Information Device Profile (MIDP) lacks low-level networking support for TCP/IP sockets and UDP/IP datagrams, but the MIDP 2.0 specification (JSR 118) has responded to the needs of the 2.5G and 3G networks now being deployed by adding support for sockets and datagrams, thus providing mobile applications more capable networking interfaces.

Wireless Software Design Techniques What every wireless software developer should know (5/02) Developing applications for devices with limited resources requires skillful developers who are willing to learn and understand how the wireless environment operates, and able to make intelligent decisions regarding software architecture and performance issues. The purpose of this article is to enlighten you about concerns you should keep in mind when developing J2ME applications.

MIDP Code Samples This page provides links to a variety of code samples that use the MIDP APIs. M-Commerce, Alerts and Timers, Event Handling, Internationalization, Network Connections, Persistent Storage, Getting Started, Servlets, User Interface...

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