I have a problem to get the extension of given file name. I receive 1 file URL.
It may be like
/var/www.dir/file.tar.gz OR /var/www.dir/file.exe
Now I need to split the file extension (like .tar.gz OR .exe) from the given URL. The URL is given by the user dynamically. Any one please help me out, how to solve this problem
This is not a terrible complicated task but one that reoccurs repeatedly. Looks like something that can be produced quickly by yourself - and it can. But you still should use a ready-made, tested library for this: Apache IO Tools, specifically FilenameUtils#getExtension. This way you avoid creepy bugs or inconsistencies. Plus you get a lot of other helpful, tested stuff.
Of course in the case of the double file extension you may need to use the methods more than once, as the library can not guess up to what level you need the extension(s). It is a .gz file, only after un-gunzipping it is a .tar file.
You could use a combination of lastIndexOf and indexOf:
String s = "/var/www.dir/file.tar.gz";
String file = s.substring(s.lastIndexOf("/"));
String extension = file.substring(file.indexOf(".")); // .tar.gz
DEMO.
You could do something like:
String str = "/var/www.dir/file.tar.gz";
Matcher m = Pattern.compile(".*/.*?(\\..*)").matcher(str);
if (m.matches()) {
fileExtension = m.group(1);
}
It seems like the simplest solution to this would be to create separate cases for the outliers (like .tar.gz) and treat the rest as the same (i.e., process out everything after the last . character).
Extensions with multiple . characters in them are so extremely uncommon that you don't need a convoluted method to parse out what you need. So:
int length = url.length();
String extension = null;
if(url.substring(length-7).equalsIgnoreCase(".tar.gz")) {
//special case
} else {
extension = url.substring(url.lastIndexOf("."));
}
I just realized that I read your question incorrectly. You could gather the extensions in a similar method, though
String yourString = "/your/whole/path.ext.si.ons";
String[] pathPieces = yourString.split("/"); // [ "your", "whole", "path.ext.si.ons" ]
String lastPiece = pathPieces[pathPieces.length - 1];
String[] namePieces = lastPiece.split("."); // [ "path", "ext", "si", "ions" ]
At this point, the first piece would probably be your name, where the rest of the pieces would be the extensions. You could then join these to have your extension type.
You can use this code to get the file extension
public static String getFileExtension(String filename)
{
if (filename == null) {
return null;
}
int lastUnixPos = filename.lastIndexOf('/');
int lastWindowsPos = filename.lastIndexOf('\\');
int indexOfLastSeparator = Math.max(lastUnixPos, lastWindowsPos);
int extensionPos = filename.lastIndexOf('.');
int lastSeparator = indexOfLastSeparator;
int indexOfExtension = lastSeparator > extensionPos ? -1 : extensionPos;
int index = indexOfExtension;
if (index == -1) {
return "";
} else {
return filename.substring(index + 1);
}
}
Assuming that URL pattern to be : "/somurl/blah-blah/filename.extension" . I would suggest the following code snippet as a solution to your problem.
String getFileExtension(String url) {
String[] urlSplit = url.split("/");
String filename = urlSplit[urlSplit.length - 1];
String[] nameSplit = filename.split("[.]");
StringBuffer fileExtension = new StringBuffer();
// to prevent appending . after extension type
if (nameSplit.length > 1) {
for (int index = 1; index < nameSplit.length; index++) {
if (index != nameSplit.length - 1)
fileExtension.append(nameSplit[index] + ".");
else
fileExtension.append(nameSplit[index]);
}
} else {
fileExtension.append(nameSplit[0]);
}
return fileExtension.toString();
}
Get the file input, then split it using a '.' as a delimiter maybe? to set a delimiter:
Scanner line_scanner = new Scanner(line).useDelimiter(".");
read the file URL twice, once for the filename and once for the extension.
