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Basic GUI problem :(

Waria Ahmed
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Joined: Jul 09, 2008
Posts: 56
Just creating a test GUI program, I have got a text field for first name and a text field for last name. In my JFrame class I am trying to take the input from firstNameTextField and in return print out the last name into the lastNameTextField. This is my code for the actionPerformed�



Basically if the text in the firstText ( variable name for my textfield) matches the first name of the person in the array. Then I want to print the second name in the text field. However I am having problems getting the text from first text field.

Can anyone shed any light on this matter please? Am I doing anything wrong?

Thanks
Joe Ess
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Joined: Oct 29, 2001
Posts: 8964
    
    9

Did you create a method "firstTextequals" or is there supposed to be a dot in there somewhere? Please be careful to Post Real Code.
Assuming that you wanted to write "firstText.equals", exactly what are you comparing to the values in the array?


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Waria Ahmed
Ranch Hand

Joined: Jul 09, 2008
Posts: 56
Yes i missed a . there but it still doesnt work.

Basically "firstText" is the variable name for the textfield, which the user types into. And whenever the user presses the search button, I want the program to take what the user typed into "firstText" and search through the array looking to see if it matches any people in array.

If it matches, I want the second name of the person to be displayed in "lastText" textfield.

I know my explanation isnt the best, so please feel free to ask further questions.

Thanks
Joe Ess
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Joined: Oct 29, 2001
Posts: 8964
    
    9

Originally posted by Waria Ahmed:

Basically "firstText" is the variable name for the textfield,


OK. So you have a textfield named "firstText". In the following comparison, what is being compared:


Hint: what is the type of firstText? What does the array contain? Can they ever be equal?
Waria Ahmed
Ranch Hand

Joined: Jul 09, 2008
Posts: 56
Im assuming the firstText is a String, and getFirstName returns a String?

i get the NullPointerException when i run the program.
Waria Ahmed
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Joined: Jul 09, 2008
Posts: 56
This is the full program if it helps...



And Person class...

Joe Ess
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Joined: Oct 29, 2001
Posts: 8964
    
    9

Originally posted by Waria Ahmed:
Im assuming the firstText is a String, and getFirstName returns a String?


Your assumption is wrong. Your code says:
Waria Ahmed
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Joined: Jul 09, 2008
Posts: 56
OHHHH Ok.... I get you.

How do I store the input from user as firstText?
Joe Ess
Bartender

Joined: Oct 29, 2001
Posts: 8964
    
    9

It should be in there if the user has typed something in.
It is a good idea to print out the values you are comparing when things aren't working the way you think they should.
Waria Ahmed
Ranch Hand

Joined: Jul 09, 2008
Posts: 56
This is the error I get when i type something and press "search"

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at uni.NewJFrame.searchButtonActionPerformed(NewJFrame.java:104)
at uni.NewJFrame.access$100(NewJFrame.java:16)
at uni.NewJFrame$2.actionPerformed(NewJFrame.java:53)
Joe Ess
Bartender

Joined: Oct 29, 2001
Posts: 8964
    
    9

It is a good idea to print out the values you are comparing when things aren't working the way you think they should.
 
I agree. Here's the link: http://aspose.com/file-tools
 
subject: Basic GUI problem :(