itemsizedemo.java

图书中的经典例子 好好看看 会有帮助的。java2me版本的

//itemSizeDemo.java file
import javax.microedition.lcdui.*;
import javax.microedition.midlet.*;

public class itemSizeDemo extends MIDlet implements CommandListener 
{
    private Command exitCommand,lockCommand, unlockCommand;
    private Form form;
    private TextField tfAddress,tfIntro;
    public itemSizeDemo()
    {
        exitCommand =new Command("Exit",Command.EXIT,1);
        lockCommand =new Command("Lock",Command.SCREEN,2);
        unlockCommand =new Command("Unlock",Command.SCREEN,2);
        
        form = new Form("unlock Demo");
        form.addCommand(exitCommand);
        form.addCommand(lockCommand);
        form.addCommand(unlockCommand);
        //设置命令监听对象
        form.setCommandListener(this);

        tfAddress = new TextField("Address","",50,TextField.ANY);
        form.append(tfAddress);
        tfIntro = new TextField("Intro","",100,TextField.ANY);
        form.append(tfIntro);
    }
    protected void startApp(  ) throws MIDletStateChangeException
    {
        Display.getDisplay(this).setCurrent(form);
    }

    protected void pauseApp(  )
    {
    }

    protected void destroyApp( boolean p1 )
    {
    }

    public void commandAction(Command c,Displayable d)
    {
        if (c ==exitCommand)
        {
            destroyApp(false);
            notifyDestroyed();
        }
        else if (c ==lockCommand)
        {
            tfIntro.setPreferredSize(-1,80);
            tfAddress.setPreferredSize(-1,60);
            form.setTitle("lock Demo");
        }
        else if (c ==unlockCommand)
        {
            tfIntro.setPreferredSize(-1 ,-1);
            tfAddress.setPreferredSize(-1 ,-1);
            form.setTitle("unlock Demo");
        }
    }
}