Problem with basic DataOutputStream script
Hi, when I run this code (below) I get this error message:
Abnormal error java.lang.ArrayIndexOutOfBoundsException: 0
I should get A-Z as my output but I don't, any ideas why?
import java.io.*;
publicclass FileWrite{
publicstaticvoid main(String[] args){
DataOutputStream os;
try
{
os =new DataOutputStream(new FileOutputStream(args[0]));
for (int n = 65; n <91;n++)
{
os.write(n);
}
}
catch (FileNotFoundException f){System.out.println("File not found " +f);}
catch (IOException io){ System.out.println("I/O error " + io);}
catch (Throwable t){System.out.println("Abnormal error " +t);}
}
}
[1626 byte] By [
kikemellya] at [2007-10-2 23:36:17]
>Abnormal error java.lang.ArrayIndexOutOfBoundsException: 0Thats because you didn't use any arguments when executing your class.BTW, its not a script - its a class.
Thanks, yeah I know its a class, been using UNIX a little latley, about the argument, isnt this part of my script ment to provide the argument.
for (int n = 65; n <91;n++)
{
os.write(n);
}
numbers 65 - 91 are the ASCII for A-Z in caps.
Mike
> args[0]You need to invoke your application with at least one command-line argument, or the above will throw the exception you are seeing.java ... FileWrite application command-line arguments go here
> Thanks, yeah I know its a class, been using UNIX a
> little latley, about the argument, isnt this part of
> my script ment to provide the argument.
What value do you think args[0] holds here that will get passed to new FileOutputStream(...)? Where do you think that value came from?
new FileOutputStream(args[0])
jverda at 2007-7-14 16:18:37 >
I dont get it, what does the value need to be to get A-Z, am I right in saying with args[0] I am passing an empty string to FileOutputStream? what do I need to pass? a file name to right too or data to process?thanks for the replies, Mike
> I dont get it, what does the value need to be to get
> A-Z, am I right in saying with args[0] I am
> passing an empty string to FileOutputStream?
No.
args is an array. It has a certain number of elements.
java MyClass ABC 123
Here, args will have 2 elements.
args[0] --> ABC
args[1] --> 123
args[2] --> ArrayIndexOutOfBoundsException
http://java.sun.com/docs/books/tutorial/java/data/arrays.html
jverda at 2007-7-14 16:18:37 >
>am I right in saying with args[0] I am passing an empty string to FileOutputStream?Even if you were right, what do you think that would do?
Okay thanks, so currently I am telling my script that the argument is element 0 of my array, which doesnt exist hence the out of bounds error. where in my script to I declare what my array is?Mike
> Okay thanks, so currently I am telling my script that> the argument is element 0 of my array, which doesnt> exist hence the out of bounds error. > > where in my script to I declare what my array is?Read reply 6 carefully.
jverda at 2007-7-14 16:18:37 >
Hey, I finally get it that i need to call my class from a DOS prompt, I was just executing it in the Sun One studio.
I am not at home to check but I guess this should work:
java FileWrite filename.txt
obviously from within the correct directory.
cheers people
Mike
BTW does anyone know if you can invoke from Sun one studio or does it have to be at a DOS prompt or BASH shell?TIAMike
Hi, can anyone tell me if there is away to invoke this script without using a command prompt, i.e. using the sun one studio, can I include anything in my script to make it invoke itself once its executed?Mike
