Scmad Chapter03


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SCMAD Review - Chapter 03 - Only for studies purposes

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Scmad Chapter03

  1. 1. By Marcel Caraciolo Chapter 03 – MIDP and MIDlets SCMAD Certification 45mm 61mm
  2. 2. Agenda <ul><li>Introduction to MIDP </li></ul><ul><li>MIDP – API’s </li></ul><ul><li>MIDlets and MIDlets Suites </li></ul>
  3. 3. MIDP: Mobile Information Device Profile <ul><li>Depends on CLDC </li></ul><ul><li>Designed for mobile phones </li></ul><ul><li>Devices must have: </li></ul><ul><ul><li>Screen (either mono, gray scale or color) </li></ul></ul><ul><ul><li>Keyboard or touchscreen </li></ul></ul><ul><ul><li>Network (limited) </li></ul></ul><ul><ul><li>Sound (rudimentary) </li></ul></ul>
  4. 4. MIDP – API’S <ul><li>Provides API’s for: </li></ul><ul><ul><li>Application life cycle and installation management </li></ul></ul><ul><ul><li>User interface </li></ul></ul><ul><ul><li>2D games </li></ul></ul><ul><ul><li>Multimedia </li></ul></ul><ul><ul><li>Persistence </li></ul></ul><ul><ul><li>Networking (HTTP 1.1 and HTTPS required) </li></ul></ul><ul><ul><li>Notifications via alarm and network </li></ul></ul><ul><ul><li>Security: Permissions and application signing </li></ul></ul><ul><ul><li>Timers </li></ul></ul>
  5. 5. MIDP – MIDlet Suites <ul><li>MIDP applications are packaged as MIDlet Suites. A </li></ul><ul><li>suite is composed of: </li></ul><ul><ul><li>JAR file with one or more MIDlets. ALL the classes that the </li></ul></ul><ul><ul><li>application depends on (the application can not depend on </li></ul></ul><ul><ul><li>classes from other JAR) and a with this Suite’s </li></ul></ul><ul><ul><li>metadata. </li></ul></ul><ul><ul><li>JAD descriptor file (not required) with Suite’s metadata (JAD is </li></ul></ul><ul><ul><li>not packaged inside the JAR). </li></ul></ul><ul><ul><li>Samples: /etc/HelloWorld.jad, /etc/ </li></ul></ul>
  6. 6. MIDP –
  7. 7. MIDP – Application descriptor (.jad)
  8. 8. MIDP – MIDlet Suites <ul><li>The application life cycle is controlled by the device. You </li></ul><ul><li>will not write a “publicstaticvoidmain” method on a </li></ul><ul><li>MIDlet, and calls to System.exit() throw a </li></ul><ul><li>SecurityException . </li></ul><ul><li>All the classes from a Suite are executed on the same VM </li></ul><ul><li>and share resources (e.g. a static getInstance() singleton is </li></ul><ul><li>shared between all the objects in the suite). </li></ul>
  9. 9. MIDP – MIDlet Suites
  10. 10. MIDP – MIDlet Suites
  11. 11. MIDP – MIDlet Suites - Review
  12. 12. MIDP - MIDlets <ul><li>Control the java application life cycle </li></ul><ul><li>Extend the javax.microedition.midlet.MIDlet </li></ul><ul><li>Sample: studyguide.cap03.HelloWorldMIDlet </li></ul><ul><li>You must code a constructor and three methods: </li></ul><ul><ul><li>startApp </li></ul></ul><ul><ul><li>pauseApp </li></ul></ul><ul><ul><li>destroyApp </li></ul></ul><ul><li>Methods shall execute quickly </li></ul><ul><li>Initializations shall be done on the constructor </li></ul><ul><li>MIDlet class must have a no-args constructor. </li></ul>
  13. 13. MIDP - startApp() <ul><li>Called when the application is started or re-activated </li></ul><ul><li>May throw MIDletStateChangeException , signalling errors </li></ul><ul><li>when the application was being activated (Temporary </li></ul><ul><li>error. User may try again later) </li></ul><ul><li>Define a screen that will be shown at initializations and re- </li></ul><ul><li>activations. </li></ul>
  14. 14. MIDP - pauseApp() <ul><li>Called by the device to signal the application will be put on </li></ul><ul><li>hold (e.g. when the device receives an incoming call). </li></ul><ul><li>Applications shall release all the resources that will not be </li></ul><ul><li>in use while the application is paused. </li></ul>
  15. 15. MIDP - destroyApp(unconditional) <ul><li>Notifies that the application is going to be finished. This </li></ul><ul><li>MIDlet’s instance will not be reused. If the application is </li></ul><ul><li>started again, a new object will be created. </li></ul><ul><li>If “unconditional “is false , the method may throw a </li></ul><ul><li>MIDletStateChangeException , so the application remains </li></ul><ul><li>running. This can be used, for instance, when the </li></ul><ul><li>application wants to confirm that the modified data may </li></ul><ul><li>be lost. If it’s true , the exception shall not be thrown </li></ul><ul><li>and the application will be finished. </li></ul><ul><li>May be called by the MIDlet itself before asking it’s </li></ul><ul><li>termination. </li></ul>
  16. 16. MIDP - MIDlet life cycle
  17. 17. MIDP - Graphic user interface model <ul><li>javax.microedition.lcdui.Display </li></ul><ul><ul><li>setCurrent : Defines the “javax.microedition.lcdui.Displayable” to </li></ul></ul><ul><ul><li>be shown. </li></ul></ul><ul><ul><li>Instance is found by calling Display.getDisplay( midlet ) and it is </li></ul></ul><ul><ul><li>valid through all the MIDlet’s life. </li></ul></ul>
  18. 18. MIDP - Super Class methods <ul><li>notifyDestroyed(), notifyPaused(), resumeRequest(): </li></ul><ul><ul><li>Called by the MIDlet to indicate that the application wishes to </li></ul></ul><ul><ul><li>change its state, to finalize, pause o re-start the execution (an </li></ul></ul><ul><ul><li>example of re-initialization request is a thread left running on </li></ul></ul><ul><ul><li>the background requesting to put the application on foreground </li></ul></ul><ul><ul><li>again). </li></ul></ul><ul><li>MIDlet.getAppProperty(key): </li></ul><ul><ul><li>Returns the value of an application property </li></ul></ul><ul><ul><li>Properties are defined on the JAD or manifest file </li></ul></ul><ul><ul><li>Applications may create its own properties, as long as they don’t </li></ul></ul><ul><ul><li>start with “MIDlet-” or “MicroEdition-” </li></ul></ul><ul><ul><li>Shall not be confused with System.getProperty(), which returns a </li></ul></ul><ul><ul><li>system property from the device (e.g. hostname, supported </li></ul></ul><ul><ul><li>OP’s, phone numbers). </li></ul></ul>
  19. 19. MIDP - Super Class methods
  20. 20. MIDP - Mandatory Attributes
  21. 21. MIDP - Optional Attributes
  22. 22. Future Work <ul><li>Next Chapter: </li></ul><ul><ul><li>MIDP -User Interface </li></ul></ul><ul><ul><li>API’s : High level, Low level, game </li></ul></ul><ul><ul><li>Displayable </li></ul></ul><ul><ul><li>Command </li></ul></ul><ul><ul><li>CommandListener </li></ul></ul><ul><ul><li>Ticker </li></ul></ul><ul><ul><li>Classes </li></ul></ul>
  23. 23. References <ul><li>ALVES F. Eduardo. SCMAD Study Guide, </li></ul><ul><li>27/04/2008. </li></ul><ul><li>JAKL Andreas, Java Platform, Micro Edition Part </li></ul><ul><li>01 slides, 12/2007. </li></ul><ul><li>Sun Certification Mobile Application Developer </li></ul><ul><li>Website: []. </li></ul>
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