Re: how to get the file extension from a pathname
In article
<2796007b-cc6d-42c0-894f-3d73330cd73c@u6g2000prc.googlegroups.com>,
jimgardener <jimgardener@gmail.com> wrote:
hi
[I] want to extract the extension of a file as a String.Suppose the
pathname of file is F:\mycode\myimage\newimg.jpg [I] need to get the
extension 'jpg' only. I did it like this,
public static void main(String [] args){
String imagetomatch=args[0];
String[] words=imagetomatch.split(java.io.File.pathSeparator);
String ext=(words[words.length-1].split("\\.")[1]);
System.out.println("ext="+ext);
}
is there a better/compact way to do this?
You might look at java.io.File#getName()
<http://java.sun.com/javase/6/docs/api/java/io/File.html#getName()>
Also, why does'nt the .split(".") work in the above case.Why do [I]
have to use .split("\\.")?
The symbol '.' represents one of the predefined character classes (any
character) in a java.util.regex.Pattern:
<http://java.sun.com/javase/6/docs/api/java/util/regex/Pattern.html>
In contrast, you're looking for the literal character '\u002E'
(full-stop, period, dot, decimal, etc.) A regex parameter containing a
single backslash ("\.") would be seen as an illegal escape character:
<http://java.sun.com/docs/books/jls/third_edition/html/lexical.html#25687
Using two backslashes signals that the second one is a literal '\'
character to be sent to the regex parser, which then uses it to escape
the special meaning of '.'.
[It's like a day at the beach, littorally.]
--
John B. Matthews
trashgod at gmail dot com
home dot woh dot rr dot com slash jbmatthews