How to create Path – Java NIO

As we know, that Path class, introduced in the Java SE 7 release, is one of the primary entry points of the java.nio.file package. If your application uses NIO, you should learn more about the powerful features available in this class. I am beginning the NIO tutorials with defining Path in NIO 2.

In this tutorial, I am listing 6 ways to create Path in NIO.

Note: 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 given below examples.

Section in this post:

Define absolute path
Define path relative to file store root
Define path relative to current working directory
Define path from URI scheme
Define path using file system default
Using System.getProperty() to build path

Let’s see the example code for all above techniques one by one:

Define absolute path

An absolute path always contains the root element and the complete directory list required to locate the file. There is no more information required further to access the file or path. We will use getPath() method with following signature.

/**
* 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);

Lets see the example in below code.

//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");

Define path relative to file store root

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

//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");

Define path relative to current working directory

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

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

Define 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. Lets see how to do it.

        //URI uri = URI.create("file:///c:/Lokesh/Setup/workspace/NIOExamples/src/sample.txt"); //OR
	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"))
	{
		System.out.println(FileSystems.getDefault().provider().getPath(uri).toAbsolutePath().toString());
	}

	//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)) {
			System.out.println(provider.getPath(uri).toAbsolutePath().toString());
			break;
		}
	}

Define path using file system default

This is another variation of above examples where instead of using Paths.get(), you can use FileSystems.getDefault().getPath() method.
The rules for absolute and relatives paths are same as above.

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

Using System.getProperty() to build path

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

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

So these were 6 ways to create NIO Path. Lets combine and run them to check their output.

package com.howtodoinjava.nio;

import static java.nio.file.FileSystems.getDefault;

import java.net.URI;
import java.nio.file.FileSystem;
import java.nio.file.FileSystems;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.spi.FileSystemProvider;

public class WorkingWithNIOPath 
{
	public static void main(String[] args)
	{
		 defineAbsolutePath();
		 defineRelativePathToRoot();
		 defineRelativePathToWorkingFolder();
		 definePathFromURI();
		 UsingFileSystemGetDefault();
		 UsingSystemProperty();
	}

	//Starts with file store root or drive
	private static void defineAbsolutePath() 
	{
		//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");
		
		System.out.println(absolutePath1.toString());
		System.out.println(absolutePath2.toString());
		System.out.println(absolutePath3.toString());
	}
	
	//Starts with a "/"
	private static void defineRelativePathToRoot() 
	{
		//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");
		
		System.out.println(relativePath1.toAbsolutePath().toString());
		System.out.println(relativePath2.toAbsolutePath().toString());
	}
	
	//Starts without a "/"
	private static void defineRelativePathToWorkingFolder() 
	{
		//How to define path relative to current working directory
		Path relativePath1 = Paths.get("src", "sample.txt");
		System.out.println(relativePath1.toAbsolutePath().toString());
	}
	
	private static void definePathFromURI() 
	{
		//URI uri = URI.create("file:///c:/Lokesh/Setup/workspace/NIOExamples/src/sample.txt"); //OR
		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"))
            System.out.println(FileSystems.getDefault().provider().getPath(uri).toAbsolutePath().toString());
        
        // try to find provider
        for (FileSystemProvider provider: FileSystemProvider.installedProviders()) {
            if (provider.getScheme().equalsIgnoreCase(scheme)) {
            	System.out.println(provider.getPath(uri).toAbsolutePath().toString());
            	break;
            }
        }
	}
	
	private static void UsingFileSystemGetDefault() {
		FileSystem fs = getDefault();
		Path path1 = fs.getPath("src/sample.txt");
		Path path2 = fs.getPath("C:/Lokesh/Setup/workspace/NIOExamples/src", "sample.txt");
		
		System.out.println(path1.toAbsolutePath().toString());
		System.out.println(path2.toAbsolutePath().toString());
	}
	
	private static void UsingSystemProperty() {
		 Path path1 = FileSystems.getDefault().getPath(System.getProperty("user.home"), "downloads", "somefile.txt");
		 System.out.println(path1.toAbsolutePath().toString());
	}

}

Output in console:

****defineAbsolutePath****
C:LokeshSetupworkspaceNIOExamplessrcsample.txt
C:LokeshSetupworkspaceNIOExamplessrcsample.txt
C:LokeshSetupworkspaceNIOExamplessrcsample.txt
****defineRelativePathToRoot****
C:LokeshSetupworkspaceNIOExamplessrcsample.txt
C:LokeshSetupworkspaceNIOExamplessrcsample.txt
****defineRelativePathToWorkingFolder****
C:LokeshSetupworkspaceNIOExamplessrcsample.txt
****definePathFromURI****
C:LokeshSetupworkspaceNIOExamplessrcsample.txt
C:LokeshSetupworkspaceNIOExamplessrcsample.txt
****UsingFileSystemGetDefault****
C:LokeshSetupworkspaceNIOExamplessrcsample.txt
C:LokeshSetupworkspaceNIOExamplessrcsample.txt
****UsingSystemProperty****
C:Usershug13902downloadssomefile.txt

Happy Learning !!