Screan对象

import javax.microedition.lcdui.Choice;
import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.List;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;


public class screemObject extends MIDlet implements CommandListener {

    Display display = null;
    public screemObject() {
        super();
    }

    protected void destroyApp(boolean arg0) throws MIDletStateChangeException {
        // TODO Auto-generated method stub

    }

    protected void pauseApp() {
        // TODO Auto-generated method stub

    }

    protected void startApp() throws MIDletStateChangeException {
        display=Display.getDisplay(this);
        List l=new List("List test",Choice.EXCLUSIVE);
        l.append("语文",null);
        l.append("数学", null);
        l.append("英语", null);
        l.setSelectedIndex(1, true);
        l.addCommand(new Command("确定",Command.OK,1));
        l.setCommandListener((CommandListener) this);
        display.setCurrent(l);
    }
    public void commandAction(Command c,Displayable d)
    {
        String cmd = c.getLabel();
        if(cmd.equals("确定"));
        {
            List l = (List)d;
            int i = l.getSelectedIndex();
            System.out.println("你选择了第 "+i+" 个选项");
            String con = l.getString(i);
            System.out.println("选项的名称为 "+ con);
        }
    }

}