Implementing the MIDlet main class

The MIDlet main class implements the required utilities and displays the main view of the MIDlet.

The MIDlet main class creates the following UI:

Figure: SystemProperties opening view

To implement the MIDlet main class:

1. Create the SystemProperties.java class file.

2. Import the required classes.

   import javax.microedition.lcdui.Alert;
   import javax.microedition.lcdui.AlertType;
   import javax.microedition.lcdui.List;
   import javax.microedition.lcdui.Command;
   import javax.microedition.lcdui.CommandListener;
   import javax.microedition.lcdui.Display;
   import javax.microedition.lcdui.Displayable;
   import javax.microedition.midlet.MIDlet;

3. Set SystemProperties to extend MIDlet and implement CommandListener. MIDlets use the CommandListener interface to receive high-level UI events from the platform.

   public class SystemProperties extends MIDlet implements CommandListener {
   

4. Create an array for each system property you want to include in the MIDlet. The properties are expressed as strings.

       //Human readable names for the properties
       private static final String[] SYSPROPLISTS = {
           "CLDC&MIDP", "Optional packages", "MMAPI (JSR-135)", "Bluetooth API (JSR-82)", "FileConnection API (JSR-75)",
           "WMA (JSR-120/205)", "SATSA API (JSR-177)", "Web Services API (JSR-172)", "AMMS API (JSR-234)",
           "Scalable 2D Vector Graphics API (JSR-226)", "Mobile 3D Graphics API (JSR-184)",
           "S60 3rd Ed. FP2 system properties", "Other Nokia system properties", "Protected system properties",
           "S60 5th Ed. properties"
       };
       //The following are names of details of system properties
       //The names of the details for the CLDC&MIDP properties
       private static final String[] CLDC_MIDPPROPS = {
           "microedition.profiles", "microedition.configuration", "microedition.locale", "microedition.platform",
           "microedition.encoding", "microedition.commports", "microedition.hostname", "microedition.jtwi.version",
           "microedition.msa.version"
       };
       private static final String[] OPT_SYSPROPS = {
           "microedition.media.version", "microedition.pim.version", "microedition.m3g.version", "microedition.location.version",
           "bluetooth.api.version", "microedition.io.file.FileConnection.version", "microedition.global.version",
           "microedition.chapi.version", "microedition.sip.version", "wireless.messaging.version", "microedition.amms.version",
           "microedition.m2g.version", "microedition.payment.version", "microedition.contactless.version", "microedition.sensor.version",
           "obex.api.version", "microedition.broadcast.version", "com.nokia.mid.ui.version"
       };
       private static final String[] MMAPI_SYSPROPS = {
           "supports.mixing", "supports.audio.capture", "supports.video.capture", "supports.recording", "audio.encodings",
           "video.encodings", "video.snapshot.encodings", "streamable.contents"
       };
       private static final String[] BT_SYSPROPS = {
           "bluetooth.l2cap.receiveMTU.max", "bluetooth.connected.devices.max", "bluetooth.connected.inquiry",
           "bluetooth.connected.page", "bluetooth.connected.inquiry.scan", "bluetooth.connected.page.scan",
           "bluetooth.master.switch", "bluetooth.sd.trans.max", "bluetooth.sd.attr.retrievable.max"
       };
       private static final String[] FILE_API_SYSPROPS = {
           "fileconn.dir.photos", "fileconn.dir.videos", "fileconn.dir.graphics", "fileconn.dir.tones",
           "fileconn.dir.music", "fileconn.dir.recordings", "fileconn.dir.memorycard", "fileconn.dir.private",
           "fileconn.dir.photos.name", "fileconn.dir.videos.name", "fileconn.dir.graphics.name", "fileconn.dir.tones.name",
           "fileconn.dir.music.name", "fileconn.dir.recordings.name", "fileconn.dir.memorycard.name",
           "fileconn.dir.private.name", "fileconn.dir.roots.names", "file.separator"
       };
       private static final String[] WMA_SYSPROPS = {
           "wireless.messaging.sms.smsc", "wireless.messaging.mms.mmsc"
       };
       private static final String[] SATSA_SYSPROPS = {
           "microedition.satsa.crypto.version", "microedition.satsa.apdu.version", "microedition.satsa.pki.version",
           "microedition.smartcardslots"
       };
       private static final String[] WEB_SERVICES_SYSPROPS = {
           "xml.jaxp.subset.version", "xml.rpc.subset.version"
       };
       private static final String[] AMMS_SYSPROPS = {
           "tuner.modulations", "audio.samplerates", "audio3d.simultaneouslocations", "camera.orientations",
           "camera.resolutions", "supports.mediacapabilities"
       };
       private static final String[] M2G_SYSPROPS = {
           "microedition.m2g.svg.baseProfile", "microedition.m2g.svg.version"
       };
       private static final String[] M3G_SYSPROPS = {
           "supportAntialiasing", "supportTrueColor", "supportDithering", "supportMipmapping",
           "supportPerspectiveCorrection", "supportLocalCameraLighting", "maxLights",
           "maxViewportWidth", "maxViewportHeight", "maxViewportDimension", "maxTextureDimension",
           "m3gRelease", "maxSpriteCropDimension", "numTextureUnits", "maxTransformsPerVertex"
       };
       private static final String[] S60_3RD_FP2_SYSPROPS = {
           // These system properties are Nokia proprietary system properties supported
           // by S60 3rd Edition Feature Pack 2 (and newer S60) devices. Note, that the access to
           // com.nokia.mid.imsi system property (in PROTECTED_SYSPROPS) is limited with
           // com.nokia.mid.Mobinfo.IMSI permission. By default this permission is available only
           // in manufacturer and operator domain.
           "com.nokia.mid.networkid", "com.nokia.mid.networksignal", "com.nokia.mid.networkavailability",
           "com.nokia.mid.networkstatus", "com.nokia.mid.batterylevel", "com.nokia.mid.countrycode",
           "com.nokia.network.access", "com.nokia.mid.dateformat", "com.nokia.mid.timeformat", "com.nokia.memoryramfree",
           "com.nokia.mid.imsi"
       };
       private static final String[] OTHER_NOKIA_SYSPROPS = {
           "com.nokia.mid.dateformat", "com.nokia.mid.timeformat", "com.nokia.network.access", "com.nokia.midp.impl.isa.network.databearer",
           "com.nokia.mid.impl.nativeDigitSupport", "com.nokia.midp.impl.isa.network.databearer", "com.nokia.mid.productcode",
           "com.nokia.mid.ui.joystick_event", "com.nokia.mid.ui.softnotification", "com.nokia.mid.ui.version", "com.nokia.keyboard.type",
           "com.nokia.key.scancode", "com.nokia.key.modifier"
       };
       private static final String[] PROTECTED_SYSPROPS = {
           "com.nokia.mid.imei", "Cell-ID", "com.nokia.mid.imsi", "com.nokia.mid.spn", "com.nokia.mid.mnc", "com.nokia.mid.ons",
           "com.nokia.mid.networkID", "com.nokia.mid.cellid", "com.nokia.mid.lac", "com.nokia.mid.gid1", "com.nokia.mid.gid2",
           "com.nokia.mid.msisdn", "com.nokia.mid.productcode"
       };
       protected static final String[] S60_5TH_SYSPROPS = {
           "com.nokia.canvas.net.indicator.location", "com.nokia.softkey1.label.location", "com.nokia.softkey2.label.location",
           "com.nokia.softkey3.label.location", "com.nokia.softkey1.label.anchor", "com.nokia.softkey2.label.anchor",
           "com.nokia.softkey3.label.anchor"
       };

5. Create the required variables and the SystemProperties class constructor.

       private List list;
       private SysPropForm form;
       private Command exitCommand;
       private Command memCommand;
       protected int index;
       protected boolean bt = false;
       protected boolean m3g = false;
   
       //Constructor
       public SystemProperties() {
           list = new List("System properties", List.IMPLICIT, SYSPROPLISTS, null);
           form = new SysPropForm(SYSPROPLISTS[0], this, CLDC_MIDPPROPS);
           exitCommand = new Command("Exit", Command.EXIT, 1);
           memCommand = new Command("Memory status", Command.SCREEN, 1);
           list.addCommand(memCommand);
           list.addCommand(exitCommand);
           list.setCommandListener(this);
           Display.getDisplay(this).setCurrent(list);
       }

6. Define the mandatory lifecycle methods for starting, pausing, and destroying the MIDlet.

       //Required when extending MIDlet
       protected void startApp() {
       }
   
       //Required when extending MIDlet
       protected void pauseApp() {
       }
   
       //Required when extending MIDlet
       protected void destroyApp(boolean p1) {
       }

7. Use the commandAction method to move to the correct screen when the user chooses to view the details of a system property.

       //Called when a command is issued
       public void commandAction(Command c, Displayable d) {
   
           //If the command is a selection, call the SysPropForm
           //which displays the details of the property.
           if (c == List.SELECT_COMMAND) {
               index = list.getSelectedIndex();
               if (index == 0) {
                   form.update(SYSPROPLISTS[0], CLDC_MIDPPROPS);
               }
               if (index == 1) {
                   form.update(SYSPROPLISTS[1], OPT_SYSPROPS);
               }
               if (index == 2) {
                   form.update(SYSPROPLISTS[2], MMAPI_SYSPROPS);
               }
               if (index == 3) {
                   bt = true;
                   form.update(SYSPROPLISTS[3], BT_SYSPROPS);
               }
               if (index == 4) {
                   form.update(SYSPROPLISTS[4], FILE_API_SYSPROPS);
               }
               if (index == 5) {
                   form.update(SYSPROPLISTS[5], WMA_SYSPROPS);
               }
               if (index == 6) {
                   form.update(SYSPROPLISTS[6], SATSA_SYSPROPS);
               }
               if (index == 7) {
                   form.update(SYSPROPLISTS[7], WEB_SERVICES_SYSPROPS);
               }
               if (index == 8) {
                   form.update(SYSPROPLISTS[8], AMMS_SYSPROPS);
               }
               if (index == 9) {
                   form.update(SYSPROPLISTS[9], M2G_SYSPROPS);
               }
               if (index == 10) {
                   m3g = true;
                   form.update(SYSPROPLISTS[10], M3G_SYSPROPS);
               }
               if (index == 11) {
                   form.update(SYSPROPLISTS[11], S60_3RD_FP2_SYSPROPS);
               }
               if (index == 12) {
                   form.update(SYSPROPLISTS[12], OTHER_NOKIA_SYSPROPS);
               }
               if (index == 13) {
                   form.update(SYSPROPLISTS[13], PROTECTED_SYSPROPS);
               }
   
               //A special case for S60_5TH_SYSPROPS
               if (index == 14) {
                   SysPropFullCanvas canvas = new SysPropFullCanvas(this);
                   Display.getDisplay(this).setCurrent(canvas);
               }
               if (index != 14) {
                   Display.getDisplay(this).setCurrent(form);
               }
           }
   
           //If the command was to show the memory status.
           if (c == memCommand) {
               showMemory();
           }
   
           //If the command was to exit the MIDlet
           if (c == exitCommand) {
               quitApp();
           }
       }
   
       public void quitApp() {
           destroyApp(true);
           notifyDestroyed();
       }

8. Create a method for displaying the opening view of the MIDlet.

       //Display the main view (list of properties)
       protected void showList() {
           Display.getDisplay(this).setCurrent(list);
       }

9. Create a method for displaying an alert window with the amount of used and available memory.

       //Show the memory notification
       private void showMemory() {
           Alert alert = new Alert("Memory status");
           String freemem = "" + Runtime.getRuntime().freeMemory();
           String totalmem = "" + Runtime.getRuntime().totalMemory();
           alert.setString("Free memory/Total memory: " + freemem + "/" + totalmem);
           alert.setType(AlertType.INFO);
           alert.setTimeout(Alert.FOREVER);
           Display.getDisplay(this).setCurrent(alert, list);
       }
   }

Now that you have implemented the MIDlet main class, implement the full screen display of property details.