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Index › Programming Questions & Help › Syntax Questions › Null pointer exception when calling a .txt
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Null pointer exception when calling a .txt (Read 2432 times)
Eau-Lit
Null pointer exception when calling a .txt
Jun 14th, 2010, 7:03am  
Hi,

The application I am creating needs a .txt file with important informations to run. When the user click on "read" the program searchs in the directory where the application is located the right document. The problem is, if there is no such file placed in a data folder next to the application, it freezes because of a "Null pointer exception". I need to tell the user in that case he has to create the folder and put the .txt file in it to run the application.

Is there a way to write a message to the user just before the Null pointer exception?
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koogy
Re: Null pointer exception when calling a .txt
Reply #1 - Jun 14th, 2010, 7:30am  
you can handle any exceptions that your code throws using try-catch

http://processing.org/reference/try.html

put the try block around the file open, and your message in the catch.
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Eau-Lit
Re: Null pointer exception when calling a .txt
Reply #2 - Jun 14th, 2010, 7:47am  
Okay I cheked the reference for Try statements and I can't find a way to identify the exception to write in the catch() parentesis.
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Eau-Lit
Re: Null pointer exception when calling a .txt
Reply #3 - Jun 14th, 2010, 7:49am  
Code:
try {
	source = loadStrings(folder+"myfile.txt"); // Trouver l'emplacement enregistré plus haut et y ajouter le nom du fichier qui contient les données.
    } 
    catch(NullPointerException e)  {
	textAlign(CENTER);
	fill(0);
	text("Impossible",width/2,height/2);
    }


This is my code for now.
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Eau-Lit
Re: Null pointer exception when calling a .txt
Reply #4 - Jun 14th, 2010, 8:03am  
Okay my error, the NullPointerException wasn't in that particular line, it was in the next lines where I filled subStrings with parts of the the .txt file. Now it does works, thanks for your reference koogy.
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