Difference between File separator and slash in paths

Question

What is the difference between using File separator and a normal   in a Java Path-String   In contrast to double backslash    platform independence seems not to be the reason  since both versions work under Windows and Unix   public class SlashTest        Test     public void slash   throws Exception           File file   new File  src trials SlashTest java            assertThat file exists    is true                Test     public void separator   throws Exception           File file   new File  src    File separator    trials    File separator    SlashTest java            assertThat file exists    is true              To rephrase the question  if   works on Unix and Windows  why should one ever want to use File separator

User · Answer

Java SE8 for Programmers  claims that the Java will cope with either   pp  480  last paragraph   The example claims that     c  Program Files Java jdk1 6 0 11 demo jfc   will parse just fine   Take note of the last  Unix-style  separator     It s tacky  and probably error-prone  but it is what they  Deitel and Deitel  claim     I think the confusion for people  rather than Java  is reason enough not to use this  mis  feature

User · Answer

OK let s inspect some code  File java lines 428 to 435 in File  lt init gt    String p   uri getPath    if  p equals          throw new IllegalArgumentException  URI path component is empty        Okay  now initialize p   fs fromURIPath p   if  File separatorChar         p   p replace      File separatorChar     And let s read fs   FileSystem    fromURIPath   docs      java io FileSystem   public abstract String fromURIPath String path    Post-process the given URI path string if necessary  This is used on   win32  e g   to transform   c  foo  into  c  foo   The path string   still has slash separators  code in the File class will translate them   after this method returns    This means FileSystem fromURIPath   does post processing on URI path only in Windows  and because in the next line   p   p replace      File separatorChar     It replaces each     with system dependent seperatorChar  you can always be sure that     is safe in every OS

User · Answer

With the Java libraries for dealing with files  you can safely use    slash  not backslash  on all platforms  The library code handles translating things into platform-specific paths internally   You might want to use File separator in UI  however  because it s best to show people what will make sense in their OS  rather than what makes sense to Java   Update  I have not been able  in five minutes of searching  to find the  you can always use a slash  behavior documented  Now  I m sure I ve seen it documented  but in the absense of finding an official reference  because my memory isn t perfect   I d stick with using File separator because you know that will work

User · Answer

As the gentlemen described the difference with variant details   I would like to recommend the use of the Apache Commons io api  class FilenameUtils when dealing with files in a program with the possibility of deploying on multiple OSs

User · Answer

Although using File separator to reference a file name is overkill  for those who imagine far off lands  I imagine their JVM implementation would replace a   with a   just like the windows jvm replaces it with a      However  sometimes you are getting the file reference  not creating it  and you need to parse it  and to be able to do that  you need to know the separator on the platform  File separator helps you do that

User · Answer

The pathname for a file or directory is specified using the naming conventions of the host system  However  the File class defines platform-dependent constants that can be used to handle file and directory names in a platform-independent way   Files seperator defines the character or string that separates the directory and the file com- ponents in a pathname  This separator is          or     for Unix  Windows  and Macintosh  respectively

User · Answer

Late to the party   I m on Windows 10 with JDK 1 8 and Eclipse MARS 1  I find that   getClass   getClassLoader   getResourceAsStream  path to resource     works and  getClass   getClassLoader   getResourceAsStream  path  File separator  to  File separator  resource     does not work and   getClass   getClassLoader   getResourceAsStream  path to resource     does not work   The last two are equivalent   So    I have good reason to NOT use File separator

User · Answer

You use File separator because someday your program might run on a platform developed in a far-off land  a land of strange things and stranger people  where horses cry and cows operate all the elevators  In this land  people have traditionally used the     character as a file separator  and so dutifully the JVM obeys their wishes

User · Answer

If you are using Java 7  checkout Path resolve   and Paths get

User · Answer

portability plain and simple

User · Answer

Although it doesn t make much difference on the way in  it does on the way back   Sure you can use either     or     in new File String path   but File getPath   will only give you one of them

User · Answer

Using File separator made Ubuntu generate files with     on it s name instead of directories  Maybe I am being lazy with how I am making files and directories  and could have avoided it  regardless  use     every time to avoid files with     on it s name

User · Answer

Well  there are more OS s than Unix and Windows  Portable devices  etc   and Java is known for its portability  The best practice is to use it  so the JVM could determine which one is the best for that OS

User · Answer

If you are trying to create a File from some ready path  saved in database  per example  using Linux separator  what should I do   Maybe just use the path do create the file   new File   shared folder file jpg      But Windows use a different separator      So  is the alternative convert the slash separator to platform independent  Like   new File convertPathToPlatformIndependent   shared folder       This method convertPathToPlatformIndependent probably will have some kind of split by     and join with File separator    Well  for me  that s not nice for a language that is platform independent  right   and Java already support the use of   on Windows or Linux  But if you are working with paths and need to remember to this conversion every single time this will be a nightmare and you won t have any real gain for the application on the future  maybe in the universe that  Pointy described

[java] Difference between File.separator and slash in paths

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