problem with double operations

[krzys waleski]

I have a problem with code. ( My version of java is CLDC 1.1, MIDP-2.0)

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

public class Midlet extends MIDlet implements CommandListener, ItemCommandListener {    
    private static final Command CMD_PRESS = new Command("Press", Command.SCREEN, 1);
    private static final Command CMD_EXIT = new Command("Exit", Command.EXIT, 1);
    
    double[] arg = new double[1];
    
    private Display display;
    private Form mainForm;
    TextField wynik;
   
    protected void startApp() {
        display = Display.getDisplay(this);
        mainForm = new Form("liczenie całki");
        mainForm.append("podaj dane:");

        StringItem item ;
        
        item = new StringItem("", "licz", Item.BUTTON);
        item.setDefaultCommand(CMD_PRESS);
        item.setItemCommandListener(this);
        mainForm.append(item);

        wynik = new TextField("tu będzie wynik", "", 15, TextField.ANY);
        mainForm.append(wynik);


        mainForm.addCommand(CMD_EXIT);
        mainForm.setCommandListener(this);
        display.setCurrent(mainForm);
    }

    public void commandAction(Command c, Item item) {
        if (c == CMD_PRESS) {
            
           // double dliczba=1.1;// it works****************************************
            double dliczba=(1.1+2.2);// it doesn't work!!
            String h = Double.toString(dliczba);
        wynik.setString(h);
        }
    }

    public void commandAction(Command c, Displayable d) {
        destroyApp(false);
        notifyDestroyed();
    }
    protected void destroyApp(boolean unconditional) {
    }
    protected void pauseApp() {
    }


} 
 

The "problematic" code is marked by asteriks.
i got the debug info:

TRACE: <at java.lang.IllegalArgumentException>, Exception caught in Display class
java.lang.IllegalArgumentException
        at javax.microedition.lcdui.TextField.setCharsImpl(), bci=79
        at javax.microedition.lcdui.TextField.setString(), bci=37
        at Midlet.commandAction(Midlet.java:43)
        at javax.microedition.lcdui.StringItemLFImpl.uCallKeyPressed(), bci=85
        at javax.microedition.lcdui.FormLFImpl.uCallKeyPressed(), bci=87
        at javax.microedition.lcdui.DisplayableLFImpl.uCallKeyEvent(), bci=146
        at javax.microedition.lcdui.Display$DisplayEventConsumerImpl.handleKeyEvent(), bci=30
        at com.sun.midp.lcdui.DisplayEventListener.process(), bci=277
        at com.sun.midp.events.EventQueue.run(), bci=179
        at java.lang.Thread.run(Thread.java:619)
    

[Darryl Burke]

Background reading: http://docs.sun.com/source/806-3568/ncg_goldberg.html

double dliczba=(1.1+2.2);// it doesn't work!! 

It "doesn't work" because

Double.toString(3.3)

is more than 15 characters in length, and the text field was constructed with a capacity of 15 characters. Add a line and the Exception goes away.

double dliczba = (1.1 + 2.2);// it doesn't work!!
String h = Double.toString(dliczba);
h = h.substring(0, 15);
wynik.setString(h);

Oh, and welcome to the Ranch!

[krzys waleski]

thanks!!