alertdemo.java~3~

J2ME高级用户界面的学习代码

//AlertDemo.java

import javax.microedition.lcdui.*;
import javax.microedition.midlet.MIDlet;

public class AlertDemo extends MIDlet implements CommandListener
{
  private final static Command CMD_EXIT = new Command("EXIT",Command.EXIT,1);
  private Alert alert;
  private Form form;
  private final int timeout = 10000;

  public AlertDemo()
  {
    try
    {
      alert = new Alert("AlertDemo","Information Alert Running",Image.createImage("/information.png"),AlertType.INFO);
      alert.setTimeout(timeout);
      Gauge indicator = createIndicator(timeout);
      alert.setIndicator(indicator);
    }
    catch(java.io.IOException e)
    {
      System.out.println(e.toString());
    }

    form = new Form("Next Screen");
    form.append("Alert has done!");
    form.addCommand(CMD_EXIT);
    form.setCommandListener(this);
  }

  protected void startApp()
  {
    Display.getDisplay(this).setCurrent(alert,form);
  }

  protected void destroyApp(boolean unconditional){}
  protected void pauseApp(){}

  public void commandAction(Command c,Displayable d)
  {
    if(c == CMD_EXIT)
    {
      destroyApp(false);
      notifyDestroyed();
    }
  }

  private Gauge createIndicator(int maxValue)
  {
    if(maxValue == Alert.FOREVER)
    {
      return new Gauge(null,false,Gauge.INDEFINITE,Gauge.CONTINUOUS_RUNNING);
    }
    final int max = maxValue/1000;//指示器的最大值
    final Gauge indicator = new Gauge(null,false,max,0);
    new Thread()
    {
      public void run()
      {
        int value = 0;
        while(value < max)
        {
          indicator.setValue(value);
          ++value;
          try
          {
            Thread.sleep(1000);
          }
          catch(InterruptedException ie){}
        }
      }
    }.start();
    return indicator;
  }
}