File.separator vs File.pathSeparator

File separator is used to construct file path. ‘/’ is the file separator in windows and ‘\’ is the file separator in Linux,

For Example

For the files f1, f2 and f3, the path looks like

f1/f2/f3 in Windows

f1\f2\f3 in Linux environment.

Following application is used to take list of file names as input and construct the path as output.

FileUtil.java

package com.sample.util;

import java.io.File;

public class FileUtil {

 private static final String EMPTY_STR = "";
 
 public static String constructPath(String[] fileNames){
  if(fileNames == null || fileNames.length == 0){
   return EMPTY_STR;
  }
  
  StringBuilder pathBuilder = new StringBuilder();
  
  for(String fileName : fileNames){
   pathBuilder.append(fileName).append(File.separator);
  }
  
  String path =  pathBuilder.toString();
  
  return path.substring(0, path.length()-1);
 }
 
}

FileUtilTest.java

package com.sample.util;

public class FileUtilTest {
 public static void main(String[] args) {
  String[] fileNames = { "f1", "f2", "f3" };

  String path = FileUtil.constructPath(fileNames);

  System.out.println(path);
 }
}

File path separator is used to combine list of file paths. ‘;’ is the file path separator in Windows, where as ‘:’ is the file path separator in Linux.

For example,

On Linux environment, paths can be combined using ‘:’ like below.

/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Library/Java/JavaVirtualMachines/jdk1.8.0_77.jdk/Contents/Home/bin:

On Windows based systems, paths can be combined using ‘;’ like below.

C:\ProgramData\Oracle\Java\javapath;%SystemRoot%\system32;%SystemRoot%;%SystemRoot%\System32\Wbem;%SYSTEMROOT%\System32\WindowsPowerShell\v1.0\;C:\Program Files (x86)\Java\jdk1.8.0_102\bin;

Following application takes list of file paths as input and combine the paths using path separator.

FileUtil.java

package com.sample.util;

import java.io.File;

public class FileUtil {

 private static final String EMPTY_STR = "";

 public static String constructPath(String[] paths) {
  if (paths == null || paths.length == 0) {
   return EMPTY_STR;
  }

  StringBuilder pathBuilder = new StringBuilder();

  for (String path : paths) {
   pathBuilder.append(path).append(File.pathSeparator);
  }

  String path = pathBuilder.toString();

  return path.substring(0, path.length() - File.pathSeparator.length());
 }

}

FileUtilTest.java

package com.sample.util;

import java.io.File;

public class FileUtilTest {
 public static void main(String[] args) {
  String path1 = "f1" + File.separator + "f2";
  String path2 = "f1" + File.separator + "f2" + File.separator + "f3";
  String path3 = "folder1" + File.separator + "folder2";

  String[] paths = { path1, path2, path3 };

  String path = FileUtil.constructPath(paths);

  System.out.println(path);
 }
}

Sample Output

f1\f2;f1\f2\f3;folder1\folder2

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