TextField error checking

[- ions]

I have created a JComboBox with its Items as a list of "M" numbers ie.
M1,M2,M3....... throgh too M110 (thes are the messier objects, a
catolouge of deep sky objects) the user selects of of these and views
it aswell as infomation. The program also has a JTextFiels which
allows the user to enter the M number. The problem i have is checking
that what the user has entered is valid, that being an M followed by 1
- 110 Nothing else, i thought of checking it against the items in the
comboBox with itemAt() but i cudnt work out a way of looping through
them, and using that within the if() Expression.... please help.

[hiwa]

Re: TextField error checking

negative_ions_0 @hotmail.com (- ions) wrote in message news:<4799447d. 0312210507.73cb 102@posting.goo gle.com>...[color=blue]
> I have created a JComboBox with its Items as a list of "M" numbers ie.
> M1,M2,M3....... throgh too M110 (thes are the messier objects, a
> catolouge of deep sky objects) the user selects of of these and views
> it aswell as infomation. The program also has a JTextFiels which
> allows the user to enter the M number. The problem i have is checking
> that what the user has entered is valid, that being an M followed by 1
> - 110 Nothing else, i thought of checking it against the items in the
> comboBox with itemAt() but i cudnt work out a way of looping through
> them, and using that within the if() Expression.... please help.[/color]
You can use InputVerifier extended class, or, more simply, you can do
the check in the ActionListener for the JTextField.

[- ions]

Re: TextField error checking

HGA03630@nifty. ne.jp (hiwa) wrote in message news:<6869384d. 0312211700.2622 2d12@posting.go ogle.com>...[color=blue]
> negative_ions_0 @hotmail.com (- ions) wrote in message news:<4799447d. 0312210507.73cb 102@posting.goo gle.com>...[color=green]
> > I have created a JComboBox with its Items as a list of "M" numbers ie.
> > M1,M2,M3....... throgh too M110 (thes are the messier objects, a
> > catolouge of deep sky objects) the user selects of of these and views
> > it aswell as infomation. The program also has a JTextFiels which
> > allows the user to enter the M number. The problem i have is checking
> > that what the user has entered is valid, that being an M followed by 1
> > - 110 Nothing else, i thought of checking it against the items in the
> > comboBox with itemAt() but i cudnt work out a way of looping through
> > them, and using that within the if() Expression.... please help.[/color]
> You can use InputVerifier extended class, or, more simply, you can do
> the check in the ActionListener for the JTextField.[/color]

Thats where my problem lies, im not sure how to acually do the
checking (its proving harder than i thought it would). It will happen
with the ActionEvent for a button. All i have at the moment is
checking that the string starts with M, which is far from what i
want...

else if( !input_selectio n.startsWith("M ")) //Not exaclly dummyproof
{
display error dialog message here....
}

[Anthony Borla]

Re: TextField error checking


"- ions" <negative_ions_ 0@hotmail.com> wrote in message
news:4799447d.0 312210507.73cb1 02@posting.goog le.com...[color=blue]
>
> I have created a JComboBox with its Items as a list of "M"
> numbers ie. M1,M2,M3....... throgh too M110 (thes are the
> messier objects, a catolouge of deep sky objects) the user
> selects of of these and views it aswell as infomation. The
> program also has a JTextFiels which allows the user to enter
> the M number. The problem i have is checking that what the
> user has entered is valid, that being an M followed by 1 - 110
> Nothing else, i thought of checking it against the items in the
> comboBox with itemAt() but i cudnt work out a way of looping
> through them, and using that within the if() Expression....
> please help.
>[/color]

You basically want to know whether a typed in value is valid i.e. conforms
to the expected format.

Code below [suitably modified] could be used to perform format checking in
your JTextField's ActionListener [i..e. you accept input after ENTER
pressed, check it with the code below, and either accept or reject the
data].

Other approaches also exist - it all depends how much effort you wish to
apply. The following link may be of help:

http://java.sun.com/docs/books/tutorial/uiswing/components/formattedtextfiel

d.html

I hope this helps.

Anthony Borla

// -----------------------------------------------------
public class TestIsValidSkyO bjectID
{
public static void main(String[] args)
{
if (args.length != 1)
{
System.err.prin tln("Usage: java TestIsValidSkyO bjectID SkyObjectID");
System.exit(1);
}

System.out.prin tln(args[0] + " is "
+ (isValidSkyObje ctID(args[0]) ? " valid" : " not valid"));
}

public static boolean isValidSkyObjec tID(String skyObjectID)
{
if (skyObjectID.ch arAt(0) != 'M')
return false;

short numericSuffix = 0;

try { numericSuffix = Short.parseShor t(skyObjectID.s ubstring(1)); }
catch (NumberFormatEx ception e) {}

if (numericSuffix < 1 || numericSuffix > 110)
return false;

return true;
}
}

// ---------------------------------------------

[Anthony Borla]

Re: TextField error checking


"- ions" <negative_ions_ 0@hotmail.com> wrote in message
news:4799447d.0 312212314.e5a35 b0@posting.goog le.com...[color=blue]
> HGA03630@nifty. ne.jp (hiwa) wrote in message[/color]
news:<6869384d. 0312211700.2622 2d12@posting.go ogle.com>...[color=blue][color=green]
> > negative_ions_0 @hotmail.com (- ions) wrote in message[/color][/color]
news:<4799447d. 0312210507.73cb 102@posting.goo gle.com>...[color=blue][color=green][color=darkred]
> > >
> > > I have created a JComboBox with its Items as a list of
> > > "M" numbers ie. M1,M2,M3....... throgh too M110
> > > (thes are the messier objects, a catolouge of deep sky
> > > objects) the user selects of of these and views it aswell
> > > as infomation. The program also has a JTextFiels which
> > > allows the user to enter the M number. The problem i
> > > have is checking that what the user has entered is valid,
> > > that being an M followed by 1 - 110 Nothing else, i
> > > thought of checking it against the items in the comboBox
> > > with itemAt() but i cudnt work out a way of looping through
> > > them, and using that within the if() Expression.... please help.[/color]
> > You can use InputVerifier extended class, or, more simply,
> > you can do the check in the ActionListener for the
> > JTextField.[/color]
>
> Thats where my problem lies, im not sure how to acually
> do the checking (its proving harder than i thought it would).
> It will happen with the ActionEvent for a button. All i have
> at the moment is checking that the string starts with M, which
> is far from what i want...
>
> else if( !input_selectio n.startsWith("M "))
> //Not exaclly dummyproof
> {
> display error dialog message here....
> }
>[/color]

A code snippet using the validation routine I earlier posted:

...
static boolean isValidSkyObjec tID(String skyObjectID)
{
...
}
...
public void actionPerformed (ActionEvent evt)
{
// Check contents of field after user has pressed ENTER
if (!isValidSkyObj ectID(inputText Field.getText() ))
{
// Warn user of input validation problem ...

// * Display a message dialog
JOptionPane.sho wMessageDialog( null,
"Invalid Sky Object - Must be M1 - M110",
"Data Validation Warning ",
JOptionPane.INF ORMATION_MESSAG E);

// * Or, update a status field / area ...
statusField.set Text("Invalid Sky Object - Must be M1 -
M110");
// ...
}

// Input ok, do work ...
// ...
}
...

You may care to check out the following tutorial for additional help:

http://java.sun.com/docs/books/tutorial/uiswing/components/textfield.html

I hope this helps.

Anthony Borla

[Todd Corley]

Re: TextField error checking

Look into javax.swing.tex t.DocumentFilte r.

It lets you do realtime editing to to changes in the document with out
worrying about firing yourself into an event loop.

Below will work for you, just add it like

yourTextField.g etDocument().ad dDocumentFilter ( new MFilter() );

Good Luck,
Todd









import javax.swing.tex t.AttributeSet;
import javax.swing.tex t.BadLocationEx ception;
import javax.swing.tex t.Document;
import javax.swing.tex t.DocumentFilte r;


public class MFilter extends DocumentFilter
{

public void insertString(Do cumentFilter.Fi lterBypass fb,
int offset,
String string,
AttributeSet attr) throws
BadLocationExce ption
{

fb.insertString (offset, string, attr);
if( !validate( fb.getDocument( ) ) )
{
fb.remove(offse t,string.length ());
}
}

public void remove(Document Filter.FilterBy pass fb,
int offset,
int length) throws BadLocationExce ption
{

String orig = fb.getDocument( ).getText(offse t,length);
fb.remove(offse t, length);
if( !validate( fb.getDocument( ) ) )
{
fb.insertString (offset,orig,nu ll);
}
}

public void replace(Documen tFilter.FilterB ypass fb,
int offset,
int length,
String text,
AttributeSet attrs) throws
BadLocationExce ption
{
String orig = fb.getDocument( ).getText(offse t,length);
text = text.toUpperCas e();
fb.replace(offs et, length, text, attrs);
if( !validate( fb.getDocument( ) ) )
{
if( orig.equals( "" ) )
{
fb.remove(offse t,text.length() );
}
else
{
fb.replace(offs et, length, orig, attrs);
}
}
}


public boolean validate(Docume nt doc )
{
boolean retVal = true;

String text = "";
try
{
text = doc.getText(0, doc.getLength() );
}
catch( Exception e )
{
}
int len = text.length();
if( len > 4 )
{
return( false );
}
if( len > 1 )
{
try
{
int val = Integer.valueOf ( text.substring( 1)
).intValue();
retVal = val > 0 && val <= 110;
}
catch( Exception exc )
{
retVal = false;
}
}
retVal = (text.charAt(0) == 'M' && retVal );
return retVal;
}
}

[- ions]

Re: TextField error checking

"Anthony Borla" <ajborla@bigpon d.com> wrote in message news:<fyxFb.613 81$aT.46044@new s-server.bigpond. net.au>...[color=blue]
> "- ions" <negative_ions_ 0@hotmail.com> wrote in message
> news:4799447d.0 312210507.73cb1 02@posting.goog le.com...[color=green]
> >
> > I have created a JComboBox with its Items as a list of "M"
> > numbers ie. M1,M2,M3....... throgh too M110 (thes are the
> > messier objects, a catolouge of deep sky objects) the user
> > selects of of these and views it aswell as infomation. The
> > program also has a JTextFiels which allows the user to enter
> > the M number. The problem i have is checking that what the
> > user has entered is valid, that being an M followed by 1 - 110
> > Nothing else, i thought of checking it against the items in the
> > comboBox with itemAt() but i cudnt work out a way of looping
> > through them, and using that within the if() Expression....
> > please help.
> >[/color]
>
> You basically want to know whether a typed in value is valid i.e. conforms
> to the expected format.
>
> Code below [suitably modified] could be used to perform format checking in
> your JTextField's ActionListener [i..e. you accept input after ENTER
> pressed, check it with the code below, and either accept or reject the
> data].
>
> Other approaches also exist - it all depends how much effort you wish to
> apply. The following link may be of help:
>
> http://java.sun.com/docs/books/tutor...mattedtextfiel
> d.html
>
> I hope this helps.
>
> Anthony Borla
>
> // -----------------------------------------------------
> public class TestIsValidSkyO bjectID
> {
> public static void main(String[] args)
> {
> if (args.length != 1)
> {
> System.err.prin tln("Usage: java TestIsValidSkyO bjectID SkyObjectID");
> System.exit(1);
> }
>
> System.out.prin tln(args[0] + " is "
> + (isValidSkyObje ctID(args[0]) ? " valid" : " not valid"));
> }
>
> public static boolean isValidSkyObjec tID(String skyObjectID)
> {
> if (skyObjectID.ch arAt(0) != 'M')
> return false;
>
> short numericSuffix = 0;
>
> try { numericSuffix = Short.parseShor t(skyObjectID.s ubstring(1)); }
> catch (NumberFormatEx ception e) {}
>
> if (numericSuffix < 1 || numericSuffix > 110)
> return false;
>
> return true;
> }
> }
>
> // ---------------------------------------------[/color]

Excellent, just what i wanted, didnt think there would of been much to it! Thanks

[Tony Morris]

Re: TextField error checking

You want to create your own Document implementation and override the public
void insertString(in t offset, String str, AttributeSet a) throws
BadLocationExce ption method.

--
Tony Morris
(BInfTech, Cert 3 I.T., SCJP[1.4], SCJD)
Software Engineer
IBM Australia - Tivoli Security Software

"- ions" <negative_ions_ 0@hotmail.com> wrote in message
news:4799447d.0 312210507.73cb1 02@posting.goog le.com...[color=blue]
> I have created a JComboBox with its Items as a list of "M" numbers ie.
> M1,M2,M3....... throgh too M110 (thes are the messier objects, a
> catolouge of deep sky objects) the user selects of of these and views
> it aswell as infomation. The program also has a JTextFiels which
> allows the user to enter the M number. The problem i have is checking
> that what the user has entered is valid, that being an M followed by 1
> - 110 Nothing else, i thought of checking it against the items in the
> comboBox with itemAt() but i cudnt work out a way of looping through
> them, and using that within the if() Expression.... please help.[/color]