Java relative paths to files

Java NIO Path (with Examples)

The Path class, introduced in the Java SE 7 release, is one of the primary entry points of the java.nio.file package. If our application uses Java New IO, we should learn more about the powerful features available in this class.

In this Java tutorial, we are learning 6 ways to create a Path .

Table of Contents 1. Building the absolute path 2. Building path relative to file store root 3. Building path relative to the current working directory 4. Building path from URI scheme 5. Building path using file system defaults 6. Building path using System.getProperty()

Prerequisite: I am building path for a file in location – “ C:/Lokesh/Setup/workspace/NIOExamples/src/sample.txt “. I have created this file beforehand and will create Path to this file in all examples.

An absolute path always contains the root element and the complete directory hierarchy required to locate the file. There is no more information required further to access the file or path.

To create an absolute path to a file, use getPath() method.

/** * Converts a path string, or a sequence of strings that when joined form a path string, * to a Path. If more does not specify any elements then the value of the first parameter * is the path string to convert. If more specifies one or more elements then each non-empty * string, including first, is considered to be a sequence of name elements and is * joined to form a path string. */ public static Path get(String first, String. more);

Example 1: Create an absolute Path to a file in Java NIO

In all given examples, we are creating the absolute path for the same file, in different ways.

//Starts with file store root or drive Path absolutePath1 = Paths.get("C:/Lokesh/Setup/workspace/NIOExamples/src", "sample.txt"); Path absolutePath2 = Paths.get("C:/Lokesh/Setup/workspace", "NIOExamples/src", "sample.txt"); Path absolutePath3 = Paths.get("C:/Lokesh", "Setup/workspace", "NIOExamples/src", "sample.txt");

2. Building path relative to file store root

Path relative to file store root starts with a forward-slash (“/”) character.

Example 2: Create relative Path to a given file

//How to define path relative to file store root (in windows it is c:/) Path relativePath1 = FileSystems .getDefault() .getPath("/Lokesh/Setup/workspace/NIOExamples/src", "sample.txt"); Path relativePath2 = FileSystems .getDefault() .getPath("/Lokesh", "Setup/workspace/NIOExamples/src", "sample.txt");

3. Building path relative to current working directory

To define the path relative to the current working directory, do not use either file system root (c:/ in windows) or slash (“/”).

Example 3: Create relative Path to current working directory

In given example, the current working directory is NIOExamples .

//How to define path relative to current working directory Path relativePath1 = Paths.get("src", "sample.txt");

4. Building path from URI scheme

Not frequently, but at times we might face a situation where we would like to convert a file path in format “file:///src/someFile.txt” to NIO path.

Example 4: Get the absolute path of a file using file URI in Java NIO

//Writing c:/ is optional //URI uri = URI.create("file:///c:/Lokesh/Setup/workspace/NIOExamples/src/sample.txt"); URI uri = URI.create("file:///Lokesh/Setup/workspace/NIOExamples/src/sample.txt"); String scheme = uri.getScheme(); if (scheme == null) throw new IllegalArgumentException("Missing scheme"); //Check for default provider to avoid loading of installed providers if (scheme.equalsIgnoreCase("file")) < String absPath = FileSystems.getDefault() .provider() .getPath(uri) .toAbsolutePath() .toString(); System.out.println(absPath); >//If you do not know scheme then use this code. //This code check file scheme as well if available. for (FileSystemProvider provider: FileSystemProvider.installedProviders()) < if (provider.getScheme().equalsIgnoreCase(scheme)) < String absPath = provider.getPath(uri) .toAbsolutePath() .toString(); System.out.println(absPath); >>

5. Building path using file system default

This is another variation of above examples where instead of using Paths.get() , we can use FileSystems.getDefault().getPath() method.

The rules for absolute and relatives paths are the same as the above methods.

Example 5: Get absolute path of a file using system defaults

FileSystem fs = FileSystems.getDefault(); //relative path Path path1 = fs.getPath("src/sample.txt"); //absolute path Path path2 = fs.getPath("C:/Lokesh/Setup/workspace/NIOExamples/src", "sample.txt");

6. Building path using System.getProperty()

Well, this is off the course, but good to know. We can use system-specific System.getProperty() also to build Path for specific files.

Example 6: Get path of a file in the system download folder

Path path1 = FileSystems.getDefault() .getPath(System.getProperty("user.home"), "downloads", "somefile.txt");

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