How to construct a relative path in Java from two absolute paths or URLs

Question

Given two absolute paths  e g    var data stuff xyz dat  var data   How can one create a relative path that uses the second path as its base  In the example above  the result should be    stuff xyz dat

User · Answer

When using java net URI relativize you should be aware of Java bug  JDK-6226081  URI should be able to relativize paths with partial roots      At the moment  the relativize   method of URI will only  relativize URIs when one is a prefix of the other    Which essentially means java net URI relativize will not create      s for you

User · Answer

Psuedo-code    Split the strings by the path seperator       Find the greatest common path by iterating thru the result of the split string  so you d end up with   var data  or   a  in your two examples  return       whicheverPathIsLonger substring commonPath length

User · Answer

It s a little roundabout  but why not use URI   It has a relativize method which does all the necessary checks for you   String path     var data stuff xyz dat   String base     var data   String relative   new File base  toURI   relativize new File path  toURI    getPath       relative     stuff xyz dat    Please note that for file path there s java nio file Path relativize since Java 1 7  as pointed out by  Jirka Meluzin in the other answer

User · Answer

If you re writing a Maven plugin  you can use Plexus  PathTool   import org codehaus plexus util PathTool   String relativeFilePath   PathTool getRelativeFilePath file1  file2

User · Answer

I know this is a bit late but  I created a solution that works with any java version      public static String getRealtivePath File root  File file                 String path   file getPath            String rootPath   root getPath            boolean plus1   path contains File separator           return path substring path indexOf rootPath    rootPath length      plus1   1   0

User · Answer

Cool   I need a bit of code like this but for comparing directory paths on Linux machines  I found that this wasn t working in situations where a parent directory was the target   Here is a directory friendly version of the method    public static String getRelativePath String targetPath  String basePath        String pathSeparator      boolean isDir   false        File f   new File targetPath      isDir   f isDirectory            We need the -1 argument to split to make sure we get a trailing          token if the base ends in the path separator and is therefore      a directory  We require directory paths to end in the path      separator -- otherwise they are indistinguishable from files   String   base   basePath split Pattern quote pathSeparator   -1    String   target   targetPath split Pattern quote pathSeparator   0         First get all the common elements  Store them as a string       and also count how many of them there are    String common        int commonIndex   0   for  int i   0  i  lt  target length  amp  amp  i  lt  base length  i           if  target i  equals base i               common    target i    pathSeparator           commonIndex                else break       if  commonIndex    0              Whoops -- not even a single common path element  This most          likely indicates differing drive letters  like C  and D             These paths cannot be relativized  Return the target path       return targetPath           This should never happen when all absolute paths          begin with   as in  nix        String relative        if  base length    commonIndex             Comment this out if you prefer that a relative path not start with         relative         pathSeparator      else        int numDirsUp   base length - commonIndex -  isDir 0 1      only subtract 1 if it  is a file              The number of directories we have to backtrack is the length of           the base path MINUS the number of common path elements  minus          one because the last element in the path isn t a directory       for  int i   1  i  lt    numDirsUp   i               relative           pathSeparator               if we are comparing directories then we   if  targetPath length    gt  common length          it s OK  it isn t a directory   relative    targetPath substring common length          return relative

User · Answer

If you know the second string is part of the first   String s1     var data stuff xyz dat   String s2     var data   String s3   s1 substring s2 length       or if you really want the period at the beginning as in your example   String s3       concat s1 substring s2 length

User · Answer

Passes D  nal s tests  the only change - if no common root it returns target path  it could be already relative   import static java util Arrays asList  import static java util Collections nCopies  import static org apache commons io FilenameUtils normalizeNoEndSeparator  import static org apache commons io FilenameUtils separatorsToUnix  import static org apache commons lang3 StringUtils getCommonPrefix  import static org apache commons lang3 StringUtils isBlank  import static org apache commons lang3 StringUtils isNotEmpty  import static org apache commons lang3 StringUtils join   import java io File  import java util ArrayList  import java util List   public class ResourceUtils        public static String getRelativePath String targetPath  String basePath  String pathSeparator            File baseFile   new File basePath           if  baseFile isFile       baseFile exists    amp  amp   basePath endsWith       amp  amp   basePath endsWith                    basePath   baseFile getParent             String target   separatorsToUnix normalizeNoEndSeparator targetPath            String base   separatorsToUnix normalizeNoEndSeparator basePath             String commonPrefix   getCommonPrefix target  base           if  isBlank commonPrefix               return targetPath replaceAll      pathSeparator            target   target replaceFirst commonPrefix               base   base replaceFirst commonPrefix                List lt String gt  result   new ArrayList lt  gt             if  isNotEmpty base               result addAll nCopies base split      length                  result addAll asList target replaceFirst           split                  return join result  pathSeparator

User · Answer

In Java 7 and later you can simply use  and in contrast to URI  it is bug free    Path relativize Path

User · Answer

If Paths is not available for JRE 1 5 runtime or maven plugin  package org afc util   import java io File  import java util LinkedList  import java util List   public class FileUtil        public static String getRelativePath String basePath  String filePath             return getRelativePath new File basePath   new File filePath               public static String getRelativePath File base  File file              List lt String gt  bases   new LinkedList lt String gt             bases add 0  base getName             for  File parent   base getParentFile    parent    null  parent   parent getParentFile                  bases add 0  parent getName                        List lt String gt  files   new LinkedList lt String gt             files add 0  file getName             for  File parent   file getParentFile    parent    null  parent   parent getParentFile                  files add 0  parent getName                        int overlapIndex   0          while  overlapIndex  lt  bases size    amp  amp  overlapIndex  lt  files size    amp  amp  bases get overlapIndex  equals files get overlapIndex                  overlapIndex                       StringBuilder relativePath   new StringBuilder            for  int i   overlapIndex  i  lt  bases size    i                  relativePath append       append File separatorChar                      for  int i   overlapIndex  i  lt  files size    i                  relativePath append files get i   append File separatorChar                      relativePath deleteCharAt relativePath length   - 1           return relativePath toString

User · Answer

Lots of answers already here  but I found they didn t handle all cases  such as the base and target being the same  This function takes a base directory and a target path and returns the relative path  If no relative path exists  the target path is returned  File separator is unnecessary   public static String getRelativePath  String baseDir  String targetPath        String   base   baseDir replace            split             targetPath   targetPath replace                 String   target   targetPath split                 Count common elements and their length      int commonCount   0  commonLength   0  maxCount   Math min target length  base length       while  commonCount  lt  maxCount            String targetElement   target commonCount           if   targetElement equals base commonCount    break          commonCount            commonLength    targetElement length     1     Directory name length plus slash            if  commonCount    0  return targetPath     No common path element       int targetLength   targetPath length        int dirsUp   base length - commonCount      StringBuffer relative   new StringBuffer dirsUp   3   targetLength - commonLength   1       for  int i   0  i  lt  dirsUp  i            relative append             if  commonLength  lt  targetLength  relative append targetPath substring commonLength        return relative toString

User · Answer

Actually my other answer didn t work if the target path wasn t a child of the base path   This should work   public class RelativePathFinder        public static String getRelativePath String targetPath  String basePath          String pathSeparator                find common path         String   target   targetPath split pathSeparator           String   base   basePath split pathSeparator            String common               int commonIndex   0          for  int i   0  i  lt  target length  amp  amp  i  lt  base length  i                   if  target i  equals base i                      common    target i    pathSeparator                  commonIndex                                      String relative                  is the target a child directory of the base directory             i e   target    a b c d  base    a b          if  commonIndex    base length                relative         pathSeparator   targetPath substring common length                       else                  determine how many directories we have to backtrack             for  int i   1  i  lt   commonIndex  i                      relative           pathSeparator                            relative    targetPath substring common length                        return relative             public static String getRelativePath String targetPath  String basePath            return getRelativePath targetPath  basePath  File pathSeparator               public class RelativePathFinderTest extends TestCase        public void testGetRelativePath             assertEquals    stuff xyz dat   RelativePathFinder getRelativePath                    var data stuff xyz dat     var data                   assertEquals        b c   RelativePathFinder getRelativePath   a b c                     a x y

User · Answer

Here a method that resolves a relative path from a base path regardless they are in the same or in a different root   public static String GetRelativePath String path  String base        final String SEP                if base is not a directory - gt  return empty     if   base endsWith SEP            return                   check if path is a file - gt  remove last     at the end of the method     boolean isfile    path endsWith SEP           get URIs and split them by using the separator     String a           String b           try           a   new File base  getCanonicalFile   toURI   getPath            b   new File path  getCanonicalFile   toURI   getPath          catch  IOException e            e printStackTrace              String   basePaths   a split SEP       String   otherPaths   b split SEP           check common part     int n   0      for   n  lt  basePaths length  amp  amp  n  lt  otherPaths length  n                   if  basePaths n  equals otherPaths n      false               break                compose the new path     StringBuffer tmp   new StringBuffer          for int m   n  m  lt  basePaths length  m             tmp append      SEP       for int m   n  m  lt  otherPaths length  m                   tmp append otherPaths m            tmp append SEP                 get path string     String result   tmp toString            remove last     if path is a file     if  isfile  amp  amp  result endsWith SEP            result   result substring 0 result length  -1              return result

User · Answer

I m assuming you have fromPath  an absolute path for a folder   and toPath  an absolute path for a folder file   and your re looking for a path that with represent the file folder in toPath as a relative path from fromPath  your current working directory is fromPath  then something like this should work   public static String getRelativePath String fromPath  String toPath          This weirdness is because a separator of     messes with String split     String regexCharacter   File separator    if  File separatorChar                regexCharacter                  String   fromSplit   fromPath split regexCharacter     String   toSplit   toPath split regexCharacter         Find the common path   int common   0    while  fromSplit common  equals toSplit common          common           StringBuffer result   new StringBuffer             Work your way up the FROM path to common ground   for  int i   common  i  lt  fromSplit length  i          result append File separatorChar  append                  Work your way down the TO path   for  int i   common  i  lt  toSplit length  i          result append File separatorChar  append toSplit i           return result toString

User · Answer

Psuedo-code    Split the strings by the path seperator       Find the greatest common path by iterating thru the result of the split string  so you d end up with   var data  or   a  in your two examples  return       whicheverPathIsLonger substring commonPath length

User · Answer

Psuedo-code    Split the strings by the path seperator       Find the greatest common path by iterating thru the result of the split string  so you d end up with   var data  or   a  in your two examples  return       whicheverPathIsLonger substring commonPath length

User · Answer

Lots of answers already here  but I found they didn t handle all cases  such as the base and target being the same  This function takes a base directory and a target path and returns the relative path  If no relative path exists  the target path is returned  File separator is unnecessary   public static String getRelativePath  String baseDir  String targetPath        String   base   baseDir replace            split             targetPath   targetPath replace                 String   target   targetPath split                 Count common elements and their length      int commonCount   0  commonLength   0  maxCount   Math min target length  base length       while  commonCount  lt  maxCount            String targetElement   target commonCount           if   targetElement equals base commonCount    break          commonCount            commonLength    targetElement length     1     Directory name length plus slash            if  commonCount    0  return targetPath     No common path element       int targetLength   targetPath length        int dirsUp   base length - commonCount      StringBuffer relative   new StringBuffer dirsUp   3   targetLength - commonLength   1       for  int i   0  i  lt  dirsUp  i            relative append             if  commonLength  lt  targetLength  relative append targetPath substring commonLength        return relative toString

User · Answer

Actually my other answer didn t work if the target path wasn t a child of the base path   This should work   public class RelativePathFinder        public static String getRelativePath String targetPath  String basePath          String pathSeparator                find common path         String   target   targetPath split pathSeparator           String   base   basePath split pathSeparator            String common               int commonIndex   0          for  int i   0  i  lt  target length  amp  amp  i  lt  base length  i                   if  target i  equals base i                      common    target i    pathSeparator                  commonIndex                                      String relative                  is the target a child directory of the base directory             i e   target    a b c d  base    a b          if  commonIndex    base length                relative         pathSeparator   targetPath substring common length                       else                  determine how many directories we have to backtrack             for  int i   1  i  lt   commonIndex  i                      relative           pathSeparator                            relative    targetPath substring common length                        return relative             public static String getRelativePath String targetPath  String basePath            return getRelativePath targetPath  basePath  File pathSeparator               public class RelativePathFinderTest extends TestCase        public void testGetRelativePath             assertEquals    stuff xyz dat   RelativePathFinder getRelativePath                    var data stuff xyz dat     var data                   assertEquals        b c   RelativePathFinder getRelativePath   a b c                     a x y

User · Answer

private String relative String left  String right       String   lefts   left split           String   rights   right split           int min   Math min lefts length  rights length       int commonIdx   -1      for int i   0  i  lt  min  i             if commonIdx  lt  0  amp  amp   lefts i  equals rights i                 commonIdx   i - 1              break                      if commonIdx  lt  0           return null            StringBuilder sb   new StringBuilder Math max left length    right length          sb append left  append           for int i   commonIdx   1  i  lt  lefts length i             sb append                   for int i   commonIdx   1  i  lt  rights length i             sb append rights i   append                  return sb deleteCharAt sb length   -1  toString

User · Answer

Here a method that resolves a relative path from a base path regardless they are in the same or in a different root   public static String GetRelativePath String path  String base        final String SEP                if base is not a directory - gt  return empty     if   base endsWith SEP            return                   check if path is a file - gt  remove last     at the end of the method     boolean isfile    path endsWith SEP           get URIs and split them by using the separator     String a           String b           try           a   new File base  getCanonicalFile   toURI   getPath            b   new File path  getCanonicalFile   toURI   getPath          catch  IOException e            e printStackTrace              String   basePaths   a split SEP       String   otherPaths   b split SEP           check common part     int n   0      for   n  lt  basePaths length  amp  amp  n  lt  otherPaths length  n                   if  basePaths n  equals otherPaths n      false               break                compose the new path     StringBuffer tmp   new StringBuffer          for int m   n  m  lt  basePaths length  m             tmp append      SEP       for int m   n  m  lt  otherPaths length  m                   tmp append otherPaths m            tmp append SEP                 get path string     String result   tmp toString            remove last     if path is a file     if  isfile  amp  amp  result endsWith SEP            result   result substring 0 result length  -1              return result

User · Answer

If Paths is not available for JRE 1 5 runtime or maven plugin  package org afc util   import java io File  import java util LinkedList  import java util List   public class FileUtil        public static String getRelativePath String basePath  String filePath             return getRelativePath new File basePath   new File filePath               public static String getRelativePath File base  File file              List lt String gt  bases   new LinkedList lt String gt             bases add 0  base getName             for  File parent   base getParentFile    parent    null  parent   parent getParentFile                  bases add 0  parent getName                        List lt String gt  files   new LinkedList lt String gt             files add 0  file getName             for  File parent   file getParentFile    parent    null  parent   parent getParentFile                  files add 0  parent getName                        int overlapIndex   0          while  overlapIndex  lt  bases size    amp  amp  overlapIndex  lt  files size    amp  amp  bases get overlapIndex  equals files get overlapIndex                  overlapIndex                       StringBuilder relativePath   new StringBuilder            for  int i   overlapIndex  i  lt  bases size    i                  relativePath append       append File separatorChar                      for  int i   overlapIndex  i  lt  files size    i                  relativePath append files get i   append File separatorChar                      relativePath deleteCharAt relativePath length   - 1           return relativePath toString

User · Answer

At the time of writing  June 2010   this was the only solution that passed my test cases  I can t guarantee that this solution is bug-free  but it does pass the included test cases  The method and tests I ve written depend on the FilenameUtils class from Apache commons IO   The solution was tested with Java 1 4  If you re using Java 1 5  or higher  you should consider replacing StringBuffer with StringBuilder  if you re still using Java 1 4 you should consider a change of employer instead    import java io File  import java util regex Pattern   import org apache commons io FilenameUtils   public class ResourceUtils                   Get the relative path from one file to another  specifying the directory separator          If one of the provided resources does not exist  it is assumed to be a file unless it ends with     or                             param targetPath targetPath is calculated to this file         param basePath basePath is calculated from this file         param pathSeparator directory separator  The platform default is not assumed so that we can test Unix behaviour when running on Windows  for example          return             public static String getRelativePath String targetPath  String basePath  String pathSeparator                Normalize the paths         String normalizedTargetPath   FilenameUtils normalizeNoEndSeparator targetPath           String normalizedBasePath   FilenameUtils normalizeNoEndSeparator basePath               Undo the changes to the separators made by normalization         if  pathSeparator equals                     normalizedTargetPath   FilenameUtils separatorsToUnix normalizedTargetPath               normalizedBasePath   FilenameUtils separatorsToUnix normalizedBasePath              else if  pathSeparator equals                      normalizedTargetPath   FilenameUtils separatorsToWindows normalizedTargetPath               normalizedBasePath   FilenameUtils separatorsToWindows normalizedBasePath              else               throw new IllegalArgumentException  Unrecognised dir separator      pathSeparator                            String   base   normalizedBasePath split Pattern quote pathSeparator            String   target   normalizedTargetPath split Pattern quote pathSeparator                First get all the common elements  Store them as a string             and also count how many of them there are          StringBuffer common   new StringBuffer             int commonIndex   0          while  commonIndex  lt  target length  amp  amp  commonIndex  lt  base length                  amp  amp  target commonIndex  equals base commonIndex                  common append target commonIndex    pathSeparator               commonIndex                       if  commonIndex    0                   No single common path element  This most                likely indicates differing drive letters  like C  and D                  These paths cannot be relativized              throw new PathResolutionException  No common path element found for      normalizedTargetPath      and      normalizedBasePath                                                      The number of directories we have to backtrack depends on whether the base is a file or a dir            For example  the relative path from                        foo bar baz gg ff to  foo bar baz                             if ff is a file                    if ff is a directory                       The following is a heuristic to figure out if the base refers to a file or dir  It s not perfect  because            the resource referred to by this path may not actually exist  but it s the best I can do         boolean baseIsFile   true           File baseResource   new File normalizedBasePath            if  baseResource exists                  baseIsFile   baseResource isFile               else if  basePath endsWith pathSeparator                 baseIsFile   false                     StringBuffer relative   new StringBuffer             if  base length    commonIndex                int numDirsUp   baseIsFile   base length - commonIndex - 1   base length - commonIndex               for  int i   0  i  lt  numDirsUp  i                      relative append        pathSeparator                                   relative append normalizedTargetPath substring common length              return relative toString                static class PathResolutionException extends RuntimeException           PathResolutionException String msg                super msg                           The test cases that this passes are  public void testGetRelativePathsUnix         assertEquals  stuff xyz dat   ResourceUtils getRelativePath   var data stuff xyz dat     var data               assertEquals        b c   ResourceUtils getRelativePath   a b c     a x y               assertEquals        b c   ResourceUtils getRelativePath   m n o a b c     m n o a x y              public void testGetRelativePathFileToFile         String target    C   Windows  Boot  Fonts  chs boot ttf       String base    C   Windows  Speech  Common  sapisvr exe        String relPath   ResourceUtils getRelativePath target  base             assertEquals          Boot  Fonts  chs boot ttf   relPath      public void testGetRelativePathDirectoryToFile         String target    C   Windows  Boot  Fonts  chs boot ttf       String base    C   Windows  Speech  Common          String relPath   ResourceUtils getRelativePath target  base             assertEquals          Boot  Fonts  chs boot ttf   relPath      public void testGetRelativePathFileToDirectory         String target    C   Windows  Boot  Fonts       String base    C   Windows  Speech  Common  foo txt        String relPath   ResourceUtils getRelativePath target  base             assertEquals          Boot  Fonts   relPath      public void testGetRelativePathDirectoryToDirectory         String target    C   Windows  Boot         String base    C   Windows  Speech  Common         String expected            Boot        String relPath   ResourceUtils getRelativePath target  base             assertEquals expected  relPath      public void testGetRelativePathDifferentDriveLetters         String target    D   sources  recovery  RecEnv exe       String base    C   Java  workspace  AcceptanceTests  Standard test data  geo          try           ResourceUtils getRelativePath target  base                 fail           catch  PathResolutionException ex               expected exception

User · Answer

When using java net URI relativize you should be aware of Java bug  JDK-6226081  URI should be able to relativize paths with partial roots      At the moment  the relativize   method of URI will only  relativize URIs when one is a prefix of the other    Which essentially means java net URI relativize will not create      s for you

User · Answer

Here is a solution other library free   Path sourceFile   Paths get  some common path example a b c f1 txt    Path targetFile   Paths get  some common path example d e f2 txt     Path relativePath   sourceFile relativize targetFile   System out println relativePath     Outputs              d e f2 txt    EDIT  actually it outputs on more     because of the source is file not a directory  Correct solution for my case is   Path sourceFile   Paths get new File  some common path example a b c f1 txt   parent     Path targetFile   Paths get  some common path example d e f2 txt     Path relativePath   sourceFile relativize targetFile   System out println relativePath

User · Answer

If you know the second string is part of the first   String s1     var data stuff xyz dat   String s2     var data   String s3   s1 substring s2 length       or if you really want the period at the beginning as in your example   String s3       concat s1 substring s2 length

User · Answer

It s a little roundabout  but why not use URI   It has a relativize method which does all the necessary checks for you   String path     var data stuff xyz dat   String base     var data   String relative   new File base  toURI   relativize new File path  toURI    getPath       relative     stuff xyz dat    Please note that for file path there s java nio file Path relativize since Java 1 7  as pointed out by  Jirka Meluzin in the other answer

User · Answer

If you know the second string is part of the first   String s1     var data stuff xyz dat   String s2     var data   String s3   s1 substring s2 length       or if you really want the period at the beginning as in your example   String s3       concat s1 substring s2 length

User · Answer

Recursion produces a smaller solution   This throws an exception if the result is impossible  e g  different Windows disk  or impractical  root is only common directory            Computes the path for a file relative to a given base  or fails if the only shared     directory is the root and the absolute form is better          param base File that is the base for the result     param name File to be  relativized      return the relative name     throws IOException if files have no common sub-directories  i e  at best share the                        root prefix     or  C         public static String getRelativePath File base  File name  throws IOException        File parent   base getParentFile         if  parent    null            throw new IOException  No common directory               String bpath   base getCanonicalPath        String fpath   name getCanonicalPath         if  fpath startsWith bpath             return fpath substring bpath length     1         else           return         File separator   getRelativePath parent  name

User · Answer

private String relative String left  String right       String   lefts   left split           String   rights   right split           int min   Math min lefts length  rights length       int commonIdx   -1      for int i   0  i  lt  min  i             if commonIdx  lt  0  amp  amp   lefts i  equals rights i                 commonIdx   i - 1              break                      if commonIdx  lt  0           return null            StringBuilder sb   new StringBuilder Math max left length    right length          sb append left  append           for int i   commonIdx   1  i  lt  lefts length i             sb append                   for int i   commonIdx   1  i  lt  rights length i             sb append rights i   append                  return sb deleteCharAt sb length   -1  toString

User · Answer

org apache ant has a FileUtils class with a getRelativePath method  Haven t tried it myself yet  but could be worthwhile to check it out   http   javadoc haefelinger it org apache ant 1 7 1 org apache tools ant util FileUtils html getRelativePath java io File  java io File

User · Answer

It s a little roundabout  but why not use URI   It has a relativize method which does all the necessary checks for you   String path     var data stuff xyz dat   String base     var data   String relative   new File base  toURI   relativize new File path  toURI    getPath       relative     stuff xyz dat    Please note that for file path there s java nio file Path relativize since Java 1 7  as pointed out by  Jirka Meluzin in the other answer

User · Answer

Psuedo-code    Split the strings by the path seperator       Find the greatest common path by iterating thru the result of the split string  so you d end up with   var data  or   a  in your two examples  return       whicheverPathIsLonger substring commonPath length

User · Answer

I m assuming you have fromPath  an absolute path for a folder   and toPath  an absolute path for a folder file   and your re looking for a path that with represent the file folder in toPath as a relative path from fromPath  your current working directory is fromPath  then something like this should work   public static String getRelativePath String fromPath  String toPath          This weirdness is because a separator of     messes with String split     String regexCharacter   File separator    if  File separatorChar                regexCharacter                  String   fromSplit   fromPath split regexCharacter     String   toSplit   toPath split regexCharacter         Find the common path   int common   0    while  fromSplit common  equals toSplit common          common           StringBuffer result   new StringBuffer             Work your way up the FROM path to common ground   for  int i   common  i  lt  fromSplit length  i          result append File separatorChar  append                  Work your way down the TO path   for  int i   common  i  lt  toSplit length  i          result append File separatorChar  append toSplit i           return result toString

User · Answer

I m assuming you have fromPath  an absolute path for a folder   and toPath  an absolute path for a folder file   and your re looking for a path that with represent the file folder in toPath as a relative path from fromPath  your current working directory is fromPath  then something like this should work   public static String getRelativePath String fromPath  String toPath          This weirdness is because a separator of     messes with String split     String regexCharacter   File separator    if  File separatorChar                regexCharacter                  String   fromSplit   fromPath split regexCharacter     String   toSplit   toPath split regexCharacter         Find the common path   int common   0    while  fromSplit common  equals toSplit common          common           StringBuffer result   new StringBuffer             Work your way up the FROM path to common ground   for  int i   common  i  lt  fromSplit length  i          result append File separatorChar  append                  Work your way down the TO path   for  int i   common  i  lt  toSplit length  i          result append File separatorChar  append toSplit i           return result toString

User · Answer

Actually my other answer didn t work if the target path wasn t a child of the base path   This should work   public class RelativePathFinder        public static String getRelativePath String targetPath  String basePath          String pathSeparator                find common path         String   target   targetPath split pathSeparator           String   base   basePath split pathSeparator            String common               int commonIndex   0          for  int i   0  i  lt  target length  amp  amp  i  lt  base length  i                   if  target i  equals base i                      common    target i    pathSeparator                  commonIndex                                      String relative                  is the target a child directory of the base directory             i e   target    a b c d  base    a b          if  commonIndex    base length                relative         pathSeparator   targetPath substring common length                       else                  determine how many directories we have to backtrack             for  int i   1  i  lt   commonIndex  i                      relative           pathSeparator                            relative    targetPath substring common length                        return relative             public static String getRelativePath String targetPath  String basePath            return getRelativePath targetPath  basePath  File pathSeparator               public class RelativePathFinderTest extends TestCase        public void testGetRelativePath             assertEquals    stuff xyz dat   RelativePathFinder getRelativePath                    var data stuff xyz dat     var data                   assertEquals        b c   RelativePathFinder getRelativePath   a b c                     a x y

User · Answer

My version is loosely based on Matt and Steve s versions          Returns the path of one File relative to another         param target the target directory     param base the base directory     return target s path relative to the base directory     throws IOException if an error occurs while resolving the files  canonical names      public static File getRelativeFile File target  File base  throws IOException       String   baseComponents   base getCanonicalPath   split Pattern quote File separator       String   targetComponents   target getCanonicalPath   split Pattern quote File separator           skip common components    int index   0     for    index  lt  targetComponents length  amp  amp  index  lt  baseComponents length    index            if   targetComponents index  equals baseComponents index           break           StringBuilder result   new StringBuilder       if  index    baseComponents length               backtrack to base directory      for  int i   index  i  lt  baseComponents length    i         result append        File separator           for    index  lt  targetComponents length    index       result append targetComponents index    File separator      if   target getPath   endsWith       amp  amp   target getPath   endsWith                     remove final path separator      result delete result length   - File separator length    result length             return new File result toString

User · Answer

Matt B s solution gets the number of directories to backtrack wrong -- it should be the length of the base path minus the number of common path elements  minus one  for the last path element  which is either a filename or a trailing    generated by split   It happens to work with  a b c  and  a x y   but replace the arguments with  m n o a b c  and  m n o a x y  and you will see the problem    Also  it needs an else break inside the first for loop  or it will mishandle paths that happen to have matching directory names  such as  a b c d  and  x y c z -- the c is in the same slot in both arrays  but is not an actual match    All these solutions lack the ability to handle paths that cannot be relativized to one another because they have incompatible roots  such as C  foo bar and D  baz quux  Probably only an issue on Windows  but worth noting   I spent far longer on this than I intended  but that s okay  I actually needed this for work  so thank you to everyone who has chimed in  and I m sure there will be corrections to this version too   public static String getRelativePath String targetPath  String basePath           String pathSeparator             We need the -1 argument to split to make sure we get a trailing             token if the base ends in the path separator and is therefore         a directory  We require directory paths to end in the path         separator -- otherwise they are indistinguishable from files      String   base   basePath split Pattern quote pathSeparator   -1       String   target   targetPath split Pattern quote pathSeparator   0            First get all the common elements  Store them as a string          and also count how many of them there are       String common           int commonIndex   0      for  int i   0  i  lt  target length  amp  amp  i  lt  base length  i              if  target i  equals base i                  common    target i    pathSeparator              commonIndex                      else break             if  commonIndex    0                    Whoops -- not even a single common path element  This most             likely indicates differing drive letters  like C  and D                These paths cannot be relativized  Return the target path          return targetPath              This should never happen when all absolute paths             begin with   as in  nix              String relative           if  base length    commonIndex                Comment this out if you prefer that a relative path not start with              relative         pathSeparator            else           int numDirsUp   base length - commonIndex - 1              The number of directories we have to backtrack is the length of              the base path MINUS the number of common path elements  minus             one because the last element in the path isn t a directory          for  int i   1  i  lt    numDirsUp   i                  relative           pathSeparator                      relative    targetPath substring common length          return relative      And here are tests to cover several cases   public void testGetRelativePathsUnixy                  assertEquals  stuff xyz dat   FileUtils getRelativePath                var data stuff xyz dat     var data               assertEquals        b c   FileUtils getRelativePath                a b c     a x y               assertEquals        b c   FileUtils getRelativePath                m n o a b c     m n o a x y              public void testGetRelativePathFileToFile          String target    C   Windows  Boot  Fonts  chs boot ttf       String base    C   Windows  Speech  Common  sapisvr exe        String relPath   FileUtils getRelativePath target  base             assertEquals              Boot  Fonts  chs boot ttf   relPath      public void testGetRelativePathDirectoryToFile          String target    C   Windows  Boot  Fonts  chs boot ttf       String base    C   Windows  Speech  Common        String relPath   FileUtils getRelativePath target  base             assertEquals          Boot  Fonts  chs boot ttf   relPath      public void testGetRelativePathDifferentDriveLetters          String target    D   sources  recovery  RecEnv exe       String base      C   Java  workspace  AcceptanceTests  Standard test data  geo              Should just return the target path because of the incompatible roots      String relPath   FileUtils getRelativePath target  base             assertEquals target  relPath

User · Answer

Matt B s solution gets the number of directories to backtrack wrong -- it should be the length of the base path minus the number of common path elements  minus one  for the last path element  which is either a filename or a trailing    generated by split   It happens to work with  a b c  and  a x y   but replace the arguments with  m n o a b c  and  m n o a x y  and you will see the problem    Also  it needs an else break inside the first for loop  or it will mishandle paths that happen to have matching directory names  such as  a b c d  and  x y c z -- the c is in the same slot in both arrays  but is not an actual match    All these solutions lack the ability to handle paths that cannot be relativized to one another because they have incompatible roots  such as C  foo bar and D  baz quux  Probably only an issue on Windows  but worth noting   I spent far longer on this than I intended  but that s okay  I actually needed this for work  so thank you to everyone who has chimed in  and I m sure there will be corrections to this version too   public static String getRelativePath String targetPath  String basePath           String pathSeparator             We need the -1 argument to split to make sure we get a trailing             token if the base ends in the path separator and is therefore         a directory  We require directory paths to end in the path         separator -- otherwise they are indistinguishable from files      String   base   basePath split Pattern quote pathSeparator   -1       String   target   targetPath split Pattern quote pathSeparator   0            First get all the common elements  Store them as a string          and also count how many of them there are       String common           int commonIndex   0      for  int i   0  i  lt  target length  amp  amp  i  lt  base length  i              if  target i  equals base i                  common    target i    pathSeparator              commonIndex                      else break             if  commonIndex    0                    Whoops -- not even a single common path element  This most             likely indicates differing drive letters  like C  and D                These paths cannot be relativized  Return the target path          return targetPath              This should never happen when all absolute paths             begin with   as in  nix              String relative           if  base length    commonIndex                Comment this out if you prefer that a relative path not start with              relative         pathSeparator            else           int numDirsUp   base length - commonIndex - 1              The number of directories we have to backtrack is the length of              the base path MINUS the number of common path elements  minus             one because the last element in the path isn t a directory          for  int i   1  i  lt    numDirsUp   i                  relative           pathSeparator                      relative    targetPath substring common length          return relative      And here are tests to cover several cases   public void testGetRelativePathsUnixy                  assertEquals  stuff xyz dat   FileUtils getRelativePath                var data stuff xyz dat     var data               assertEquals        b c   FileUtils getRelativePath                a b c     a x y               assertEquals        b c   FileUtils getRelativePath                m n o a b c     m n o a x y              public void testGetRelativePathFileToFile          String target    C   Windows  Boot  Fonts  chs boot ttf       String base    C   Windows  Speech  Common  sapisvr exe        String relPath   FileUtils getRelativePath target  base             assertEquals              Boot  Fonts  chs boot ttf   relPath      public void testGetRelativePathDirectoryToFile          String target    C   Windows  Boot  Fonts  chs boot ttf       String base    C   Windows  Speech  Common        String relPath   FileUtils getRelativePath target  base             assertEquals          Boot  Fonts  chs boot ttf   relPath      public void testGetRelativePathDifferentDriveLetters          String target    D   sources  recovery  RecEnv exe       String base      C   Java  workspace  AcceptanceTests  Standard test data  geo              Should just return the target path because of the incompatible roots      String relPath   FileUtils getRelativePath target  base             assertEquals target  relPath

User · Answer

Recursion produces a smaller solution   This throws an exception if the result is impossible  e g  different Windows disk  or impractical  root is only common directory            Computes the path for a file relative to a given base  or fails if the only shared     directory is the root and the absolute form is better          param base File that is the base for the result     param name File to be  relativized      return the relative name     throws IOException if files have no common sub-directories  i e  at best share the                        root prefix     or  C         public static String getRelativePath File base  File name  throws IOException        File parent   base getParentFile         if  parent    null            throw new IOException  No common directory               String bpath   base getCanonicalPath        String fpath   name getCanonicalPath         if  fpath startsWith bpath             return fpath substring bpath length     1         else           return         File separator   getRelativePath parent  name

User · Answer

My version is loosely based on Matt and Steve s versions          Returns the path of one File relative to another         param target the target directory     param base the base directory     return target s path relative to the base directory     throws IOException if an error occurs while resolving the files  canonical names      public static File getRelativeFile File target  File base  throws IOException       String   baseComponents   base getCanonicalPath   split Pattern quote File separator       String   targetComponents   target getCanonicalPath   split Pattern quote File separator           skip common components    int index   0     for    index  lt  targetComponents length  amp  amp  index  lt  baseComponents length    index            if   targetComponents index  equals baseComponents index           break           StringBuilder result   new StringBuilder       if  index    baseComponents length               backtrack to base directory      for  int i   index  i  lt  baseComponents length    i         result append        File separator           for    index  lt  targetComponents length    index       result append targetComponents index    File separator      if   target getPath   endsWith       amp  amp   target getPath   endsWith                     remove final path separator      result delete result length   - File separator length    result length             return new File result toString

User · Answer

If you re writing a Maven plugin  you can use Plexus  PathTool   import org codehaus plexus util PathTool   String relativeFilePath   PathTool getRelativeFilePath file1  file2

User · Answer

Here is a solution other library free   Path sourceFile   Paths get  some common path example a b c f1 txt    Path targetFile   Paths get  some common path example d e f2 txt     Path relativePath   sourceFile relativize targetFile   System out println relativePath     Outputs              d e f2 txt    EDIT  actually it outputs on more     because of the source is file not a directory  Correct solution for my case is   Path sourceFile   Paths get new File  some common path example a b c f1 txt   parent     Path targetFile   Paths get  some common path example d e f2 txt     Path relativePath   sourceFile relativize targetFile   System out println relativePath

User · Answer

Since Java 7 you can use the relativize method   import java nio file Path  import java nio file Paths   public class Test         public static void main String   args            Path pathAbsolute   Paths get   var data stuff xyz dat            Path pathBase   Paths get   var data            Path pathRelative   pathBase relativize pathAbsolute           System out println pathRelative              Output   stuff xyz dat

User · Answer

I m assuming you have fromPath  an absolute path for a folder   and toPath  an absolute path for a folder file   and your re looking for a path that with represent the file folder in toPath as a relative path from fromPath  your current working directory is fromPath  then something like this should work   public static String getRelativePath String fromPath  String toPath          This weirdness is because a separator of     messes with String split     String regexCharacter   File separator    if  File separatorChar                regexCharacter                  String   fromSplit   fromPath split regexCharacter     String   toSplit   toPath split regexCharacter         Find the common path   int common   0    while  fromSplit common  equals toSplit common          common           StringBuffer result   new StringBuffer             Work your way up the FROM path to common ground   for  int i   common  i  lt  fromSplit length  i          result append File separatorChar  append                  Work your way down the TO path   for  int i   common  i  lt  toSplit length  i          result append File separatorChar  append toSplit i           return result toString

User · Answer

org apache ant has a FileUtils class with a getRelativePath method  Haven t tried it myself yet  but could be worthwhile to check it out   http   javadoc haefelinger it org apache ant 1 7 1 org apache tools ant util FileUtils html getRelativePath java io File  java io File

User · Answer

It s a little roundabout  but why not use URI   It has a relativize method which does all the necessary checks for you   String path     var data stuff xyz dat   String base     var data   String relative   new File base  toURI   relativize new File path  toURI    getPath       relative     stuff xyz dat    Please note that for file path there s java nio file Path relativize since Java 1 7  as pointed out by  Jirka Meluzin in the other answer

User · Answer

Cool   I need a bit of code like this but for comparing directory paths on Linux machines  I found that this wasn t working in situations where a parent directory was the target   Here is a directory friendly version of the method    public static String getRelativePath String targetPath  String basePath        String pathSeparator      boolean isDir   false        File f   new File targetPath      isDir   f isDirectory            We need the -1 argument to split to make sure we get a trailing          token if the base ends in the path separator and is therefore      a directory  We require directory paths to end in the path      separator -- otherwise they are indistinguishable from files   String   base   basePath split Pattern quote pathSeparator   -1    String   target   targetPath split Pattern quote pathSeparator   0         First get all the common elements  Store them as a string       and also count how many of them there are    String common        int commonIndex   0   for  int i   0  i  lt  target length  amp  amp  i  lt  base length  i           if  target i  equals base i               common    target i    pathSeparator           commonIndex                else break       if  commonIndex    0              Whoops -- not even a single common path element  This most          likely indicates differing drive letters  like C  and D             These paths cannot be relativized  Return the target path       return targetPath           This should never happen when all absolute paths          begin with   as in  nix        String relative        if  base length    commonIndex             Comment this out if you prefer that a relative path not start with         relative         pathSeparator      else        int numDirsUp   base length - commonIndex -  isDir 0 1      only subtract 1 if it  is a file              The number of directories we have to backtrack is the length of           the base path MINUS the number of common path elements  minus          one because the last element in the path isn t a directory       for  int i   1  i  lt    numDirsUp   i               relative           pathSeparator               if we are comparing directories then we   if  targetPath length    gt  common length          it s OK  it isn t a directory   relative    targetPath substring common length          return relative

User · Answer

Passes D  nal s tests  the only change - if no common root it returns target path  it could be already relative   import static java util Arrays asList  import static java util Collections nCopies  import static org apache commons io FilenameUtils normalizeNoEndSeparator  import static org apache commons io FilenameUtils separatorsToUnix  import static org apache commons lang3 StringUtils getCommonPrefix  import static org apache commons lang3 StringUtils isBlank  import static org apache commons lang3 StringUtils isNotEmpty  import static org apache commons lang3 StringUtils join   import java io File  import java util ArrayList  import java util List   public class ResourceUtils        public static String getRelativePath String targetPath  String basePath  String pathSeparator            File baseFile   new File basePath           if  baseFile isFile       baseFile exists    amp  amp   basePath endsWith       amp  amp   basePath endsWith                    basePath   baseFile getParent             String target   separatorsToUnix normalizeNoEndSeparator targetPath            String base   separatorsToUnix normalizeNoEndSeparator basePath             String commonPrefix   getCommonPrefix target  base           if  isBlank commonPrefix               return targetPath replaceAll      pathSeparator            target   target replaceFirst commonPrefix               base   base replaceFirst commonPrefix                List lt String gt  result   new ArrayList lt  gt             if  isNotEmpty base               result addAll nCopies base split      length                  result addAll asList target replaceFirst           split                  return join result  pathSeparator

User · Answer

The bug referred to in another answer is addressed by URIUtils in Apache HttpComponents  public static URI resolve URI baseURI                            String reference       Resolves a URI reference against a   base URI  Work-around for bug in   java net URI

User · Answer

At the time of writing  June 2010   this was the only solution that passed my test cases  I can t guarantee that this solution is bug-free  but it does pass the included test cases  The method and tests I ve written depend on the FilenameUtils class from Apache commons IO   The solution was tested with Java 1 4  If you re using Java 1 5  or higher  you should consider replacing StringBuffer with StringBuilder  if you re still using Java 1 4 you should consider a change of employer instead    import java io File  import java util regex Pattern   import org apache commons io FilenameUtils   public class ResourceUtils                   Get the relative path from one file to another  specifying the directory separator          If one of the provided resources does not exist  it is assumed to be a file unless it ends with     or                             param targetPath targetPath is calculated to this file         param basePath basePath is calculated from this file         param pathSeparator directory separator  The platform default is not assumed so that we can test Unix behaviour when running on Windows  for example          return             public static String getRelativePath String targetPath  String basePath  String pathSeparator                Normalize the paths         String normalizedTargetPath   FilenameUtils normalizeNoEndSeparator targetPath           String normalizedBasePath   FilenameUtils normalizeNoEndSeparator basePath               Undo the changes to the separators made by normalization         if  pathSeparator equals                     normalizedTargetPath   FilenameUtils separatorsToUnix normalizedTargetPath               normalizedBasePath   FilenameUtils separatorsToUnix normalizedBasePath              else if  pathSeparator equals                      normalizedTargetPath   FilenameUtils separatorsToWindows normalizedTargetPath               normalizedBasePath   FilenameUtils separatorsToWindows normalizedBasePath              else               throw new IllegalArgumentException  Unrecognised dir separator      pathSeparator                            String   base   normalizedBasePath split Pattern quote pathSeparator            String   target   normalizedTargetPath split Pattern quote pathSeparator                First get all the common elements  Store them as a string             and also count how many of them there are          StringBuffer common   new StringBuffer             int commonIndex   0          while  commonIndex  lt  target length  amp  amp  commonIndex  lt  base length                  amp  amp  target commonIndex  equals base commonIndex                  common append target commonIndex    pathSeparator               commonIndex                       if  commonIndex    0                   No single common path element  This most                likely indicates differing drive letters  like C  and D                  These paths cannot be relativized              throw new PathResolutionException  No common path element found for      normalizedTargetPath      and      normalizedBasePath                                                      The number of directories we have to backtrack depends on whether the base is a file or a dir            For example  the relative path from                        foo bar baz gg ff to  foo bar baz                             if ff is a file                    if ff is a directory                       The following is a heuristic to figure out if the base refers to a file or dir  It s not perfect  because            the resource referred to by this path may not actually exist  but it s the best I can do         boolean baseIsFile   true           File baseResource   new File normalizedBasePath            if  baseResource exists                  baseIsFile   baseResource isFile               else if  basePath endsWith pathSeparator                 baseIsFile   false                     StringBuffer relative   new StringBuffer             if  base length    commonIndex                int numDirsUp   baseIsFile   base length - commonIndex - 1   base length - commonIndex               for  int i   0  i  lt  numDirsUp  i                      relative append        pathSeparator                                   relative append normalizedTargetPath substring common length              return relative toString                static class PathResolutionException extends RuntimeException           PathResolutionException String msg                super msg                           The test cases that this passes are  public void testGetRelativePathsUnix         assertEquals  stuff xyz dat   ResourceUtils getRelativePath   var data stuff xyz dat     var data               assertEquals        b c   ResourceUtils getRelativePath   a b c     a x y               assertEquals        b c   ResourceUtils getRelativePath   m n o a b c     m n o a x y              public void testGetRelativePathFileToFile         String target    C   Windows  Boot  Fonts  chs boot ttf       String base    C   Windows  Speech  Common  sapisvr exe        String relPath   ResourceUtils getRelativePath target  base             assertEquals          Boot  Fonts  chs boot ttf   relPath      public void testGetRelativePathDirectoryToFile         String target    C   Windows  Boot  Fonts  chs boot ttf       String base    C   Windows  Speech  Common          String relPath   ResourceUtils getRelativePath target  base             assertEquals          Boot  Fonts  chs boot ttf   relPath      public void testGetRelativePathFileToDirectory         String target    C   Windows  Boot  Fonts       String base    C   Windows  Speech  Common  foo txt        String relPath   ResourceUtils getRelativePath target  base             assertEquals          Boot  Fonts   relPath      public void testGetRelativePathDirectoryToDirectory         String target    C   Windows  Boot         String base    C   Windows  Speech  Common         String expected            Boot        String relPath   ResourceUtils getRelativePath target  base             assertEquals expected  relPath      public void testGetRelativePathDifferentDriveLetters         String target    D   sources  recovery  RecEnv exe       String base    C   Java  workspace  AcceptanceTests  Standard test data  geo          try           ResourceUtils getRelativePath target  base                 fail           catch  PathResolutionException ex               expected exception

User · Answer

I know this is a bit late but  I created a solution that works with any java version      public static String getRealtivePath File root  File file                 String path   file getPath            String rootPath   root getPath            boolean plus1   path contains File separator           return path substring path indexOf rootPath    rootPath length      plus1   1   0

User · Answer

The bug referred to in another answer is addressed by URIUtils in Apache HttpComponents  public static URI resolve URI baseURI                            String reference       Resolves a URI reference against a   base URI  Work-around for bug in   java net URI

User · Answer

In Java 7 and later you can simply use  and in contrast to URI  it is bug free    Path relativize Path

User · Answer

If you know the second string is part of the first   String s1     var data stuff xyz dat   String s2     var data   String s3   s1 substring s2 length       or if you really want the period at the beginning as in your example   String s3       concat s1 substring s2 length

User · Answer

Actually my other answer didn t work if the target path wasn t a child of the base path   This should work   public class RelativePathFinder        public static String getRelativePath String targetPath  String basePath          String pathSeparator                find common path         String   target   targetPath split pathSeparator           String   base   basePath split pathSeparator            String common               int commonIndex   0          for  int i   0  i  lt  target length  amp  amp  i  lt  base length  i                   if  target i  equals base i                      common    target i    pathSeparator                  commonIndex                                      String relative                  is the target a child directory of the base directory             i e   target    a b c d  base    a b          if  commonIndex    base length                relative         pathSeparator   targetPath substring common length                       else                  determine how many directories we have to backtrack             for  int i   1  i  lt   commonIndex  i                      relative           pathSeparator                            relative    targetPath substring common length                        return relative             public static String getRelativePath String targetPath  String basePath            return getRelativePath targetPath  basePath  File pathSeparator               public class RelativePathFinderTest extends TestCase        public void testGetRelativePath             assertEquals    stuff xyz dat   RelativePathFinder getRelativePath                    var data stuff xyz dat     var data                   assertEquals        b c   RelativePathFinder getRelativePath   a b c                     a x y

User · Answer

Since Java 7 you can use the relativize method   import java nio file Path  import java nio file Paths   public class Test         public static void main String   args            Path pathAbsolute   Paths get   var data stuff xyz dat            Path pathBase   Paths get   var data            Path pathRelative   pathBase relativize pathAbsolute           System out println pathRelative              Output   stuff xyz dat

[java] How to construct a relative path in Java from two absolute paths (or URLs)?

Examples related to java

Examples related to url

Examples related to file

Examples related to path