I wanted to get sub string

Question

Currently I am using code like this

    while (fileName.endsWith(".csv")) {
        fileName = fileName.substring(0, fileName.lastIndexOf(FILE_SUFFIX_CSV));
        if (fileName.trim().isEmpty()) {
            throw new IllegalArgumentException();
        }
    }

The above code works fine when user specifies extension in small letters(.csv),But windows accepts extensions case sensitive so he can give like .CsV ,.CSV etc. how can I alter above code ?

Thanks in Advance

This has already been answered here - http://stackoverflow.com/questions/13620555/case-sensitive-file-extension-and-existence-checking — Ashwin Venkatesh Prabhu, Sep 25 '14 at 06:04

score 13 · Accepted Answer · edited Sep 25 '14 at 06:01

13

why don't you turn it to lowercase?

while (fileName.toLowerCase().endsWith(".csv")) {
    fileName = fileName.substring(0, fileName.toLowerCase().lastIndexOf(FILE_SUFFIX_CSV));
    if (fileName.trim().isEmpty()) {
        throw new IllegalArgumentException();
    }
}

edited Sep 25 '14 at 06:01

Seelenvirtuose

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answered Sep 25 '14 at 05:54

Madhawa Priyashantha

9,633
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`filename.lastIndexOf(...)` has the same problem. This must also be converted to lower case. Besides that: This is the answer! – Seelenvirtuose Sep 25 '14 at 05:56
@Seelenvirtuose this is the answer, unless you need to preserve case in the file name, which is rather likely. – Thomas Stets Sep 25 '14 at 05:58
@ThomasStets With `fileName.toLowerCase().lastIndexOf(FILE_SUFFIX_CSV)` you are _not_ changing the variable. You are only changing the calculation of the index. The variable `fileName` is still substituted with a substring of the _original_ string (`fileName.substring(...)`). – Seelenvirtuose Sep 25 '14 at 05:59
@ThomasStets: indeed, this answer does not subvert the fileName variable whatsoever since Strings **are immutable**. 1+ to the answer. – Hovercraft Full Of Eels Sep 25 '14 at 19:00

score 5 · Answer 2 · answered Sep 25 '14 at 06:05

Late night regex solution:

Pattern pattern = Pattern.compile(".csv", Pattern.CASE_INSENSITIVE);
Matcher matcher = pattern.matcher(fileName);
while (matcher.find()) {
    fileName = fileName.substring(0, matcher.start());
    if (fileName.trim().isEmpty()) {
        throw new IllegalArgumentException();
    }
}

The Matcher will only find() once. It can then report its start position which you can use to substring the original file name.

score 4 · Answer 3 · answered Sep 25 '14 at 05:55

4

You can try this way

 int lastIndexOfDot=fileName.lastIndexOf("\\.");
 String fileExtension=fileName.substring(lastIndexOfDot+1,fileName.length()); 
 while(fileExtension.equalsIgnoreCase(".csv")){

 }

Or

while(fileName.toUpperCase().endsWith(".CSV"){}

answered Sep 25 '14 at 05:55

Ruchira Gayan Ranaweera

34,993
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score 4 · Answer 4 · answered Sep 25 '14 at 05:58

Please convert to lowercase and then compare.

  while (fileName.toLowerCase().endsWith(".csv")) {
        fileName = fileName.toLowerCase().substring(0, fileName.toLowerCase().lastIndexOf(FILE_SUFFIX_CSV));
        if (fileName.toLowerCase().trim().isEmpty()) {
            throw new IllegalArgumentException();
        }
    }

score 3 · Answer 5 · answered Sep 25 '14 at 05:55

3

You can convert both to uppercase.

So change this line

fileName = fileName.substring(0, fileName.lastIndexOf(FILE_SUFFIX_CSV));

to

fileName = fileName.toUpperCase().substring(0, fileName.lastIndexOf(FILE_SUFFIX_CSV.toUpperCase()));

answered Sep 25 '14 at 05:55

Ninad Pingale

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score 0 · Answer 6 · answered Oct 15 '19 at 10:58

use this utility function:

public static boolean endsWithIgnoreCase(String str, String suffix)
{
    int suffixLength = suffix.length();
    return str.regionMatches(true, str.length() - suffixLength, suffix, 0, suffixLength);
}

now you can do:

while (endsWithIgnoreCase(fileName, ".csv")) {
    fileName = fileName.substring(0, fileName.toLowerCase().lastIndexOf(FILE_SUFFIX_CSV));
    if (fileName.trim().isEmpty()) {
        throw new IllegalArgumentException();
    }
}

I wanted to get sub string

6 Answers6