Solved

Java: Empty string warning

Posted on 2009-04-02
10
1,389 Views
Last Modified: 2012-05-06

Dear Experts:

I have a following code.
This code works fine. But  
________________________________________________
if   ( balTxt.getText().trim( ).equals ( "") )
     JOptionPane.showMessageDialog(this, "Enter your balance");
__________________________________________________

I got an empty string warning as below:
Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: empty String
      at sun.misc.FloatingDecimal.readJavaFormatString(Unknown Source)
      at java.lang.Float.parseFloat(Unknown Source)
____________________________________________________

I need to put a proper exception code.

Can you kindly instruct me how to do that!

Thanks!
0
Comment
Question by:duta
  • 3
  • 3
  • 2
  • +2
10 Comments
 
LVL 15

Assisted Solution

by:fsze88
fsze88 earned 50 total points
ID: 24050306
try {
// do somethings
} catch (java.lang.NumberFormatException e){

}
0
 
LVL 27

Expert Comment

by:mrcoffee365
ID: 24050434
You should ideally check whether  balTxt.getText() is null before you try to run the trim method on it.  That's the source of your exception.
0
 
LVL 3

Expert Comment

by:avdej
ID: 24050911
Hi duta!

I think the solution to your problem is rather simple.
I suppose the NumberFormatException you have mentioned here has nothing to do with prompting the user:
    if   ( balTxt.getText().trim( ).equals ( "") ) ...

but happens where you try to actually PARSE a float from the user provided empty string.

To tell you more and to provide the right solution I need some more surrounding code (inclusive the line which initiates a  balTxt-parsing).

0
Free Tool: Postgres Monitoring System

A PHP and Perl based system to collect and display usage statistics from PostgreSQL databases.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

 

Author Comment

by:duta
ID: 24051416
Thank you so much.

My code is:

_________________________
{  if    (  ( balTxt.getText().trim( ).equals ( "") )
                  || ( creditLimitTxt.getText().trim( ).equals ( "") ) )
           
           
            {    
                       System.out.print ( " Enter your bal and credit limit");
           
            }
       
             
    else
           
                      process  ( );
               }
______________________________________________
0
 
LVL 3

Accepted Solution

by:
avdej earned 200 total points
ID: 24051871
Duta, one more time, the code you provided is not the cause of the problem.

You get the Exception BECAUSE you SEND an empty string to sun.misc.FloatingDecimal.readJavaFormatString() method (see javadoc here: http://www.docjar.com/docs/api/sun/misc/FloatingDecimal.html#readJavaFormatString(String))

1. Find THE line in your code where you do THIS, i.e. send a string fetched from a text field to method sun.misc.FloatingDecimal.readJavaFormatString()
2. Block THIS method call (using if-checks for string emptiness etc. and prompting the user) until the user has provided an acceptable input.
0
 
LVL 27

Assisted Solution

by:mrcoffee365
mrcoffee365 earned 150 total points
ID: 24051918
The exception is caused by this line:
if   ( balTxt.getText().trim( ).equals ( "") )

Change it to

if   ( balTxt != null && balTxt.getText() != null && balTxt.getText().trim( ).equals ( "") )


Then add a section to handle those error conditions as well:

if   ( balTxt == null || balTxt.getText() == null )
0
 
LVL 92

Assisted Solution

by:objects
objects earned 100 total points
ID: 24054964
I agress with avdej, you're calling parseFloat() with an empty string.
the full stack trace should tell you where it is occurring

0
 

Author Comment

by:duta
ID: 24055317
Thank all of you for your kind, patient help.

I am a very beginner, and I have a hard time implementing your valuable tips.

I am so sorry about that.
0
 
LVL 27

Expert Comment

by:mrcoffee365
ID: 24056409
No need to apologize -- we've all been beginners.

Make the code change I've posted for you, and let us know what happens for you.

At that point you can start debugging in other parts of your code, as "objects" and avdej are interested in having you do.
0
 

Author Comment

by:duta
ID: 24056425
Thanks a lot for very nice words.

I will take time to try your kind tips.

0

Featured Post

Free Tool: Port Scanner

Check which ports are open to the outside world. Helps make sure that your firewall rules are working as intended.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
map related example 6 55
Error in @AspectJ Based AOP with Spring 2 18
maven module vs maven project 3 46
Java: The Public Class Main 4 32
For beginner Java programmers or at least those new to the Eclipse IDE, the following tutorial will show some (four) ways in which you can import your Java projects to your Eclipse workbench. Introduction While learning Java can be done with…
Introduction Java can be integrated with native programs using an interface called JNI(Java Native Interface). Native programs are programs which can directly run on the processor. JNI is simply a naming and calling convention so that the JVM (Java…
Viewers learn how to read error messages and identify possible mistakes that could cause hours of frustration. Coding is as much about debugging your code as it is about writing it. Define Error Message: Line Numbers: Type of Error: Break Down…
This tutorial will introduce the viewer to VisualVM for the Java platform application. This video explains an example program and covers the Overview, Monitor, and Heap Dump tabs.

861 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question