Make a file of desired size using java ?

[Rahul Sudip Bose]

Please suggest some ways to make java code which generates a file of size entered by the user. The range can be from a few bytes (bits also possible ???) to many megabytes.
Thanks.

[Jesper de Jong]

What data should the file contain, or does it not matter?

You can just open a FileOutputStream and write as many bytes to it as is necessary. You cannot create a file with a fractional number of bytes (for example, a file with 4 bits).

[Rahul Sudip Bose]

Jesper de Jong wrote:What data should the file contain, or does it not matter?

Random characters. Does the code change according to the data that this file may contain ? Please give examples.

[Wouter Oet]

It might depending on what you want to do. Just open one of many tutorials about I/O and see for yourself.

[Rob Spoor]

You don't need to actually write anything, using RandomAccessFile:

RandomAccessFile raf = new RandomAccessFile(file, "rw");
try
{
    raf.setLength(newSize);
}
finally
{
    raf.close();
}

I can use this to create an 8GB file within a second. The file will use 0 to fill the file.

[Rahul Sudip Bose]

Rob Spoor wrote:You don't need to actually write anything, using RandomAccessFile:

RandomAccessFile raf = new RandomAccessFile(file, "rw");
try
{
    raf.setLength(newSize);
}
finally
{
    raf.close();
}

I can use this to create an 8GB file within a second. The file will use 0 to fill the file.

Thanks ! I tried that and it works well.

[Rahul Sudip Bose]

Thanks ! I needed it for my app here