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java – Split string on the last occurrence of some character

Posted by: admin April 23, 2020 Leave a comment

Questions:

I’m basically trying to split a string on the last period to capture the file extension. But sometimes the file doesn’t have any extension, so I’m anticipating that.

But the problem is that some file names have periods before the end like so…

/mnt/sdcard/OG Ron C, Chopstars & Drake - Choppin Ain't The Same-2013-MIXFIEND/02 Drake - Connect (Feat. Fat Pat) (Chopped Not Slopped).mp3

So when that string comes up it chops it at “02 Drake – Connect (Feat.”

This is what I’ve been using…

String filePath = intent.getStringExtra(ARG_FILE_PATH);
String fileType = filePath.substring(filePath.length() - 4);
String FileExt = null;
try {
    StringTokenizer tokens = new StringTokenizer(filePath, ".");
    String first = tokens.nextToken();
    FileExt = tokens.nextToken();
}
catch(NoSuchElementException e) {
    customToast("the scene you chose, has no extension :(");
}
System.out.println("EXT " + FileExt);
File fileToUpload = new File(filePath);

How do I split the string at the file extension but also be able to handle and alert when the file has no extension.

How to&Answers:

It might be easier to just assume that files which end with a dot followed by alphanumeric characters have extensions.

int p=filePath.lastIndexOf(".");
String e=filePath.substring(p+1);
if( p==-1 || !e.matches("\w+") ){/* file has no extension */}
else{ /* file has extension e */ }

See the Java docs for regular expression patterns. Remember to escape the backslash because the pattern string needs the backslash.

Answer:

You can try this

int i = s.lastIndexOf(c);
String[] a =  {s.substring(0, i), s.substring(i)};

Answer:

Is this Java? If so, why don’t you use “java.io.File.getName”.

For example:

File f = new File("/aaa/bbb/ccc.txt");
System.out.println(f.getName());

Out:

ccc.txt

Answer:

How about splitting the filPath using the period as separator. And taking the last item in that array to get the extension:

        String fileTypeArray[] = filePath.split(",");
        String fileType = "";
        if(fileTypeArray != null && fileTypeArray.length > 0) {
          fileType = fileTypeArray[fileTypeArray.length - 1];
        }