Introduction to Mobile programming(J2ME)
Download as PPTX, PDF2 likes6,071 views
J2ME is a Java platform for small computing devices like mobile phones and PDAs. It uses a stripped-down Java API and virtual machine called CLDC. The J2ME architecture has three layers - configuration, profile, and MIDP. The configuration defines the JVM, profiles provide features for device classes, and MIDP is the most popular profile for mobile information devices. MIDP applications are called MIDlets, which are packaged in JAR files along with optional JAD descriptor files.
Introduction to Mobile programming(J2ME)
- 1. PROGRAMMING WITH J2ME Mr. A.W.Wambua
- 2. Sun Microsystems has defined three Java platforms, to the needs of different of computing environments: • Java 2 Standard Edition (J2SE)-(Desktops) • Java 2 Enterprise Edition (J2EE)-(server-client) • Java 2 Micro Edition (J2ME)-(Small computing Devices eg Mobiles,PDAs,etc) J2ME : a reduced version of the Java API and Java Virtual Machine that is designed to operate within the sparse resources available in the new breed of embedded computers and microcomputers.
- 4. Small computing devices differ greatly eg: in terms of Memory, Storage Capability, display and connectivity To address this, Java Community Process Program( Sun’s group mandated to create J2ME) came up with an achitecture. The J2ME architecture comprises three software layers 1. Configuration layer 2. Profile Layer 3. Mobile Information Device Profile (MIDP) Layer
- 6. Basically the Architecture comprises J2ME Configurations J2ME Profiles. Configuration: defines the Java Virtual Machine for a particular small computing device. 2 configurations exist. 1. Connected Limited Device Configuration (CLDC) 2. Connected Device Configuration (CDC).
- 7. 16-bit or 32-bit small computing devices with limited amounts of memory. 160KB to 512KB of available memory . Battery powered. Use an inconsistent, small-bandwidth network wireless connection May not have a user interface. Use the KJava Virtual Machine (KVM) implementation, which is a stripped-down version of the JVM. They include pagers, personal digital assistants, cell phones, dedicated terminals, and handheld consumer devices with between 128KB and 512KB of memory.
- 8. CDC devices use a 32-bit architecture. At least 2MB of memory available. Implement a complete functional JVM. They include digital set-top boxes, home appliances, navigation systems, point-of-sale terminals, and smart phones.
- 9. A profile: consists of Java classes that enable implementation of features for either a particular small computing device or for a class of small computing devices. Several profiles exist. I. Foundation Profile. II. Game Profile. III. Mobile Information Device Profile. IV. PDA Profile. V. Personal Profile. VI. Personal Basis Profile. VII. RMI Profile.
- 10. The most popular and well known of all the profiles is the Mobile Information Device Profile (MIDP), sometimes called the MID Profile. The MIDP layers and the CLDC and defines a set of user interface (UI) APIs designed for contemporary wireless devices. MIDP applications are called MIDlets. A MIDlet is a Java application that uses the MIDP profile and the CLDC configuration.
- 11. screen size at least 96x54 pixels display depth of 1 bit One or two-handed keyboard, touch screen input device 128 KB nonvolatile memory for MIDP components 8 KB nonvolatile memory for applicationpersistent data(DB) 32 KB volatile runtime memory for Java heap two-way wireless connectivity
- 12. The MIDP, specifies the following APIs: application (MIDP application semantics and control) user interface persistent storage networking Timers
- 13. MIDP Package Name Description javax.microedition.lcdui UI classes and interfaces javax.microedition.rms Record management system (RMS) supporting persistent device storage javax.microedition.midlet MIDP application definition support class types javax.microedition.io MIDP generic connection framework classes and interfaces java.io Standard Java IO classes and interfaces java.lang VM classes and interfaces java.util Standard utility classes and interfaces
- 14. A single application could have many Midlets. Midlets are bundled into a Midletsuit contained within a single package. All files necessary to implement a midlet suit are contained in a production package called JAR(Java Archive) These include;- Midlet classes, Icons and the manifest file. Manifest file has information required by the Application manager to handle the midlets such as name , version ,vendor ..etc
- 15. Java application descriptor (JAD) file can be included within the JAR. Used to pass parameters to a MIDlet without modifying the JAR file . Provides the application manager with additional content information about the JAR file to determine whether the MIDlet suite can be implemented on the device. Attributes include : name , vendor,version of the midlet.
- 16. Code to Implement “Hello Word “ program
- 18. What is J2ME,How does it differ from J2EE? Explain the architecture of J2ME What is a Profile? What is a Configuration? Compare CDC devices to CDLC devices giving examples of each device category What is a MIDLET? What is MIDP? What are the Java Packages used in MIDP and their functions. Differentiate JAR from JAD files