How do I trim a file extension from a String in Java

Question

What s the most efficient way to trim the suffix in Java  like this   title part1 txt title part2 html   gt  title part1 title part2

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String foo    title part1 txt   foo   foo substring 0  foo lastIndexOf

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private String trimFileExtension String fileName           String   splits   fileName split                return StringUtils remove  fileName        splits splits length - 1

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Keeping in mind the scenarios where there is no file extension or there is more than one file extension  example Filename   file   file txt   file tar bz2             param fileName     return file extension    example file fastq gz   gt  fastq gz     private String extractFileExtension String fileName        String type    undefined       if  FilenameUtils indexOfExtension fileName     -1            String fileBaseName   FilenameUtils getBaseName fileName           int indexOfExtension   -1          while  fileBaseName contains                     indexOfExtension   FilenameUtils indexOfExtension fileBaseName               fileBaseName   FilenameUtils getBaseName fileBaseName                     type   fileName substring indexOfExtension   1  fileName length               return type

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As using the String substring and String lastIndex in a one-liner is good  there are some issues in terms of being able to cope with certain file paths   Take for example the following path   a b c   Using the one-liner will result in   a   That s incorrect   The result should have been c  but since the file lacked an extension  but the path had a directory with a   in the name  the one-liner method was tricked into giving part of the path as the filename  which is not correct   Need for checks  Inspired by skaffman s answer  I took a look at the FilenameUtils removeExtension method of the Apache Commons IO   In order to recreate its behavior  I wrote a few tests the new method should fulfill  which are the following    Path                  Filename --------------        -------- a b c                 c a b c jpg             c a b c jpg jpg         c jpg  a b c                 c a b c jpg             c a b c jpg jpg         c jpg  c                     c c jpg                 c c jpg jpg             c jpg    And that s all I ve checked for -- there probably are other checks that should be in place that I ve overlooked    The implementation  The following is my implementation for the removeExtension method   public static String removeExtension String s         String separator   System getProperty  file separator        String filename          Remove the path upto the filename      int lastSeparatorIndex   s lastIndexOf separator       if  lastSeparatorIndex    -1            filename   s        else           filename   s substring lastSeparatorIndex   1                 Remove the extension      int extensionIndex   filename lastIndexOf           if  extensionIndex    -1          return filename       return filename substring 0  extensionIndex       Running this removeExtension method with the above tests yield the results listed above   The method was tested with the following code  As this was run on Windows  the path separator is a   which must be escaped with a   when used as part of a String literal   System out println removeExtension  a  b  c     System out println removeExtension  a  b  c jpg     System out println removeExtension  a  b  c jpg jpg      System out println removeExtension  a b  c     System out println removeExtension  a b  c jpg     System out println removeExtension  a b  c jpg jpg      System out println removeExtension  c     System out println removeExtension  c jpg     System out println removeExtension  c jpg jpg       The results were   c c c jpg c c c jpg c c c jpg   The results are the desired results outlined in the test the method should fulfill

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I found coolbird s answer particularly useful   But I changed the last result statements to   if  extensionIndex    -1    return s   return s substring 0  lastSeparatorIndex 1              filename substring 0  extensionIndex    as I wanted the full path name to be returned   So  C  Users mroh004 COM Documents Test Test xml  becomes      C  Users mroh004 COM Documents Test Test  and not     Test

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str substring 0  str lastIndexOf

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public static String removeExtension String file        if file    null  amp  amp  file length    gt  0            while file contains                     file   file substring 0  file lastIndexOf                            return file

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If you use Spring you could use org springframework util StringUtils stripFilenameExtension String path    Strip the filename extension from the given Java resource path  e g   quot mypath myfile txt quot  - gt   quot mypath myfile quot   Params  path     the file path Returns  the path with stripped filename extension

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String fileName  foo bar   int dotIndex fileName lastIndexOf       if dotIndex gt  0       to prevent exception if there is no dot   fileName fileName substring 0 dotIndex       Is this a trick question   p  I can t think of a faster way atm

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I would do like this   String title part    title part1 txt   int i  for i title part length  -1   i gt  0  amp  amp  title part charAt i         i--   title part   title part substring 0 i     Starting to the end till the     then call substring   Edit  Might not be a golf but it s effective

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This is the sort of code that we shouldn t be doing ourselves  Use libraries for the mundane stuff  save your brain for the hard stuff   In this case  I recommend using FilenameUtils removeExtension   from Apache Commons IO

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you can try this function   very basic   public String getWithoutExtension String fileFullPath       return fileFullPath substring 0  fileFullPath lastIndexOf

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org apache commons io FilenameUtils version 2 4 gives the following answer  public static String removeExtension String filename        if  filename    null            return null            int index   indexOfExtension filename       if  index    -1            return filename        else           return filename substring 0  index            public static int indexOfExtension String filename        if  filename    null            return -1            int extensionPos   filename lastIndexOf EXTENSION SEPARATOR       int lastSeparator   indexOfLastSeparator filename       return lastSeparator  gt  extensionPos   -1   extensionPos     public static int indexOfLastSeparator String filename        if  filename    null            return -1            int lastUnixPos   filename lastIndexOf UNIX SEPARATOR       int lastWindowsPos   filename lastIndexOf WINDOWS SEPARATOR       return Math max lastUnixPos  lastWindowsPos      public static final char EXTENSION SEPARATOR        private static final char UNIX SEPARATOR        private static final char WINDOWS SEPARATOR

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create a new file with string image path  String imagePath  File test   new File imagePath   test getName    test getPath    getExtension test getName       public static String getExtension String uri            if  uri    null                return null                     int dot   uri lastIndexOf               if  dot  gt   0                return uri substring dot             else                  No extension              return

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Use a regex   This one replaces the last dot  and everything after it   String baseName   fileName replaceAll                     You can also create a Pattern object if you want to precompile the regex

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BTW  in my case  when I wanted a quick solution to remove a specific extension  this is approximately what I did     if  filename endsWith ext       return filename substring 0 filename length   - ext length       else     return filename

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filename substring filename lastIndexOf       filename length    toLowerCase

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String   splitted   fileName split       String fileNameWithoutExtension   fileName replace       splitted splitted length - 1

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String img    example jpg      String imgLink    http   www example com example jpg   URI uri   null   try       uri   new URI img       String   segments   uri getPath   split           System out println segments segments length-1  split        0      catch  Exception e        e printStackTrace        This will output example for both img and imgLink

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Use a method in com google common io Files class if your project is already dependent on Google core library  The method you need is getNameWithoutExtension

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The best what I can write trying to stick to the Path class  Path removeExtension Path path        return path resolveSibling path getFileName   toString   replaceFirst  quot           quot    quot  quot

[java] How do I trim a file extension from a String in Java?

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