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javafile-io
David Locke
David Locke

Reputation: 18074

Can I write to the end of a 5GB file in Java?

Can I write to the end of a 5GB file in Java? This question came up in my office and no one is sure what the answer is.

Upvotes: 6

Views: 6160

Answers (5)

Filip Ekberg
Filip Ekberg

Reputation: 36287

Actually that would depend on the underlying File System and how the JVM on that platform implements the File Stream. Because, if a file is bigger than 5GB you cannot, with a 32Bit operative system open the whole file and just write to it, because of the 4.3 Billion limit stuff ( 32^2 ).

So, the answer shortly would be, Yes, it is possible, IF Java handles the file correctly and the File System is a good one :)

Upvotes: 2

sblundy
sblundy

Reputation: 61414

5GB? I wonder if the OS is a bigger problem, but that's doubtful.

In theory, you can just open the file in append mode.

OutputStream in = new java.io.FileOutputStream(fileName, true);

and write till the filesystem fills up.

See Bill the Lizard for char data.

Upvotes: 0

Bill the Lizard
Bill the Lizard

Reputation: 405765

If you just mean that you need to append to the file, check out the 

FileWriter(File file, boolean append)

constructor in the FileWriter class.

Sorry, I don't have a 5GB file handy to test with. :)

Upvotes: 1

Greg Case
Greg Case

Reputation: 47421

This should be possible fairly easily using a RandomAccessFile. Something like the following should work:

String filename;

RandomAccessFile myFile = new RandomAccessFile(filename, "rw");

// Set write pointer to the end of the file
myFile.seek(myFile.length());

// Write to end of file here

Upvotes: 13

OscarRyz
OscarRyz

Reputation: 199224

Yes. Take a look at this link RandomAccessFile

http://java.sun.com/javase/6/docs/api/java/io/RandomAccessFile.html#seek(long)

That is , you open the file, and then set the position to the end of the file. And start writing from there.

Tell us how it went.

Upvotes: 6

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