Removing duplicate extension files on Java

Question

Having a folder with the following files

myoutput.pdf
hello.pdf.pdf
byebye.txt
hey.txt.txt

How can I remove the extension of ONLY the files with a duplicated extension? In the example there are only pdf and txt, but in the real example can be any type of extension.

I got this far:

String dir = "C:/Users/test";

File[] files = new File(dir).listFiles();

for (File file : files) {
    if (file.isFile()) {
        System.out.println(file.getName());
    }
}

But I don't know how can I now detected the ones with "duplicated extension" and rename it to a "single extension"

My desired output would be:

myoutput.pdf
hello.pdf
byebye.txt
hey.txt

Thanks in advance.

score 3 · Accepted Answer · answered Nov 08 '16 at 11:13

3

You may use

file.getName().replaceAll("(\\.\\w+)\\1+$", "$1")

See the regex demo

Pattern details:

(\\.\\w+) - Group 1 capturing a dot and 1 or more word chars (\\w+ might be replaced with [^.]+ to match 1 or more chars other than a dot)
\\1+ - one or more occurrences of the same value captured in Group 1
$ - end of string.

The replacement pattern is just the backreference to Group 1 ($1) to only have 1 single occurrence of the extension.

answered Nov 08 '16 at 11:13

Wiktor Stribiżew

607,720
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Thanks, that prints me the correct filename, but how can I now "rename" the file? I tried `file.renameTo(file.getName().replaceAll("(\\.\\w+)\\1+$", "$1"));` but it's not working. – Avión Nov 08 '16 at 11:16

score 0 · Answer 2 · answered Nov 08 '16 at 11:23

0

You can replace the code as below:

if (file.isFile()) {
    String newFileName = file.getName().replaceAll("(\\.\\w+)\\1+$", "$1");
    file.renameTo(new File(file.getParent() + "/" +newFileName));
}

answered Nov 08 '16 at 11:23

Umais Gillani

608
4
9

Removing duplicate extension files on Java

2 Answers2