(easy) splitting a file name into parts

[Andy Fish]

Hi,

I want to rename a file to have a different extension, but I can't find
anything in java.io.File that has any concept of file extension.

I realise this is probably operating system specific if not
application-specific but since the two biggest OSs use file extensions
extensively(!), I was expecting java.io to provide some utility functions to
manipulate them. FWIW I define the file extension as the bit following the
final dot in the file name but I'm happy to accept someone else's
definition.

Andy

 

[Chris Smith]

I want to rename a file to have a different extension, but I can't find
anything in java.io.File that has any concept of file extension.

I realise this is probably operating system specific if not
application-specific but since the two biggest OSs use file extensions
extensively(!), I was expecting java.io to provide some utility functions to
manipulate them. FWIW I define the file extension as the bit following the
final dot in the file name but I'm happy to accept someone else's
definition.

Well, that last bit seems like a reasonable definition to me. In that
case, see String.lastIndexOf and String.substring for easy ways to
manipulate the extension on a file.

--
www.designacourse.com
The Easiest Way to Train Anyone... Anywhere.

Chris Smith - Lead Software Developer/Technical Trainer
MindIQ Corporation

 

[Roedy Green]

I want to rename a file to have a different extension, but I can't find
anything in java.io.File that has any concept of file extension.

see http://mindprod.coml/jgloss/file.html for sample code.

basically search for last .

Properly should stop on last / \ also since some people put dots in
directory names.

 

[Roedy Green]

Nawww

java.io.File.isFile()

If you are parsing the entire unqualified name yourself, and you scan
backwards for . you don't want it to count if it occurs prior to the
last "/", i.e. in one of the directory node names.

You want to scan only the filename proper, e.g. new File ( f ).
getName();

 

[Jon A. Cruz]

If you are parsing the entire unqualified name yourself, and you scan
backwards for . you don't want it to count if it occurs prior to the
last "/", i.e. in one of the directory node names.

You want to scan only the filename proper, e.g. new File ( f ).
getName();

Exactly.

I had assumed that, since it's been covered many times.

File thing = new File( f );
if ( thing.isFile() )
{
int pos = thing.getName().lastIndexOf( '.' );
if ( pos > -1 )
{
...
}
}

of course, if pos == 0, you now have the tricky problem of deciding if
it's a blank name with only an extension, or if it's a hidden unix-ish
file with no extension.