Reading a file into an array.

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Stephen - 06 Mar 2004 15:09 GMT

Hi. I have a file that will be typed into something like notepad and I would
like my program to read the file line-by-line, putting each line into an
array. In Visual Basic it was very simple. Is there an equivalent to this in
Java:

Open "test.txt" for input as #1
for a = 1 to 10
input #1, array(a)
next
Close #1

I want to use showOpenDialog which stores the file in a File object. Thanks

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Christophe Vanfleteren - 06 Mar 2004 15:18 GMT

> Hi. I have a file that will be typed into something like notepad and I
> would like my program to read the file line-by-line, putting each line
[quoted text clipped - 9 lines]
> I want to use showOpenDialog which stores the file in a File object.
> Thanks

Use a FileReader:

http://java.sun.com/j2se/1.4.2/docs/api/java/io/FileReader.html

Tutorial on IO:

http://java.sun.com/docs/books/tutorial/essential/io/filestreams.html

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Kind regards,
Christophe Vanfleteren

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Jon A. Cruz - 06 Mar 2004 18:54 GMT

> Use a FileReader:
>
> http://java.sun.com/j2se/1.4.2/docs/api/java/io/FileReader.html

Just be careful. The FileReader will use the default encoding. That's
not always the best thing.

Usually you'll want to create a FileInputStream around your File.

File f;
...
FileInputStream fin = new FileInputStream(f);

Then if you want characters it can be wrapped in an InputStreamReader
using an explicit encoding.

http://java.sun.com/docs/books/tutorial/essential/io/processing.html

InputStreamReader in = new InputStreamReader(fin, "Cp1252");

Then you'd probably want to wrap things with a LineNumberInputStream and
just read from that.

The encoding name matters because unlike VB where characters are 8-bit,
Java characters are 16-bit Unicode, so you always are peforming a
transformation. It's just a matter of whether or not it's hidden from
you. Hidden makes it easier to program, but much easier for tricky hard
to find bugs to get in.

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Reading a file into an array.

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