www.pudn.com > 20051122095286.zip > ExampleMIDlet.java

package ora.ch3; 
 
import java.util.Timer; 
import java.util.TimerTask; 
import javax.microedition.midlet.MIDlet; 
import javax.microedition.midlet.MIDletStateChangeException; 
 
public class ExampleMIDlet extends MIDlet { 
     
    // Flag to indicate first call to startApp 
    private boolean started = false; 
     
    // Background thread 
    private Thread thread; 
     
    // Timer interval 
    private int timerInterval; 
     
    // Timer 
    private Timer timer; 
     
    // Task to run via the timer 
    private TimerTask task; 
     
    // Required public constructor. Can be 
    // omitted if nothing to do and no other 
    // constructors are created. 
    public ExampleMIDlet() { 
        System.out.println("Constructor executed"); 
         
        // Get the timer interval from the  
        // manifest or JAD file. 
        String interval = getAppProperty("Timer-Interval"); 
        timerInterval = Integer.parseInt(interval);  
        System.out.println("Timer interval is " + interval); 
    } 
         
    protected void startApp() throws MIDletStateChangeException { 
        if (!started) { 
            // First invocation. Create and start 
            // a timer. 
            started = true;             
            System.out.println("startApp called for the first time"); 
            startTimer(); 
        } else { 
            // Resumed after pausing.  
            System.out.println("startApp called following pause"); 
        } 
         
        // In all cases, start a background thread. 
        synchronized (this) { 
            if (thread == null) { 
                thread = new Thread() { 
                    public void run() { 
                        System.out.println("Thread running"); 
                        while (thread == this) { 
                            try { 
                                Thread.sleep(1000); 
                                System.out.println("Thread still active"); 
                            } catch (InterruptedException ex) { 
                            } 
                        } 
                        System.out.println("Thread terminating"); 
                    } 
                }; 
            } 
        } 
        thread.start(); 
    } 
 
    protected void pauseApp() { 
        // Called from the timer task to 
        // do whatever is necessary to  
        // pause the MIDlet. 
        // Tell the background thread to stop. 
        System.out.println("pauseApp called."); 
        synchronized (this) { 
            if (thread != null) { 
                thread = null; 
            } 
        } 
    } 
 
    protected void destroyApp(boolean unconditional)  
                            throws MIDletStateChangeException { 
        // Called to destroy the MIDlet. 
        System.out.println("destroyApp called - unconditional = "  
                            + unconditional); 
        if (thread != null) { 
            Thread bgThread = thread; 
            thread = null;      // Signal thread to die 
            try { 
                bgThread.join(); 
            } catch (InterruptedException ex) { 
            } 
        } 
        stopTimer(); 
    } 
     
    // Starts a timer to run a simple task 
    private void startTimer() { 
         
        // Create a task to be run 
        task = new TimerTask() { 
            private boolean isPaused; 
            private int count; 
         
            public void run() { 
                // Pause or resume the MIDlet. 
                System.out.println("Timer scheduled"); 
                if (count++ == 4) { 
                    // Terminate the MIDlet 
                    try { 
                        ExampleMIDlet.this.destroyApp(true); 
                    } catch (MIDletStateChangeException ex) { 
                        // Ignore pleas for mercy! 
                    } 
                    ExampleMIDlet.this.notifyDestroyed(); 
                    return; 
                } 
                if (isPaused) { 
                    System.out.println(">> Resuming MIDlet"); 
                    ExampleMIDlet.this.resumeRequest(); 
                    isPaused = false; 
                } else { 
                    System.out.println(">> Pausing MIDlet"); 
                    isPaused = true; 
                    ExampleMIDlet.this.pauseApp(); 
                    ExampleMIDlet.this.notifyPaused(); 
                }                 
            } 
        }; 
         
        // Create a timer and schedule it to run 
        timer = new Timer(); 
        timer.schedule(task, timerInterval, timerInterval);  
        System.out.println("Timer started."); 
    } 
     
    // Stops the timer 
    private void stopTimer() { 
        if (timer != null) { 
            System.out.println("Stopping the timer"); 
            timer.cancel(); 
        } 
    } 
}