Java NIO - Path


As name suggests Path is the particular location of an entity such as file or a directory in a file system so that one can search and access it at that particular location.

Technically in terms of Java, Path is an interface which is introduced in Java NIO file package during Java version 7,and is the representation of location in particular file system.As path interface is in Java NIO package so it get its qualified name as java.nio.file.Path.

In general path of an entity could be of two types one is absolute path and other is relative path.As name of both paths suggests that absolute path is the location address from the root to the entity where it locates while relative path is the location address which is relative to some other path.Path uses delimiters in its definition as "\" for Windows and "/" for unix operating systems.

In order to get the instance of Path we can use static method of java.nio.file.Paths class get().This method converts a path string, or a sequence of strings that when joined form a path string, to a Path instance.This method also throws runtime InvalidPathException if the arguments passed contains illegal characters.

As mentioned above absolute path is retrieved by passing root element and the complete directory list required to locate the file.While relative path could be retrieved by combining the base path with the relative path.Retrieval of both paths would be illustrated in following example

Example

package com.java.nio;
import java.io.IOException;
import java.nio.Buffer;
import java.nio.ByteBuffer;
import java.nio.file.FileSystem;
import java.nio.file.LinkOption;
import java.nio.file.Path;
import java.nio.file.Paths;
public class PathDemo {
   public static void main(String[] args) throws IOException {
      Path relative = Paths.get("file2.txt");
      System.out.println("Relative path: " + relative);
      Path absolute = relative.toAbsolutePath();
      System.out.println("Absolute path: " + absolute);
   }
}

So far we know that what is path interface why do we need that and how could we access it.Now we would know what are the important methods which Path interface provide us.

Important methods of Path Interface

  • getFileName() − Returns the file system that created this object.

  • getName() − Returns a name element of this path as a Path object.

  • getNameCount() − Returns the number of name elements in the path.

  • subpath() − Returns a relative Path that is a subsequence of the name elements of this path.

  • getParent() − Returns the parent path, or null if this path does not have a parent.

  • getRoot() − Returns the root component of this path as a Path object, or null if this path does not have a root component.

  • toAbsolutePath() − Returns a Path object representing the absolute path of this path.

  • toRealPath() − Returns the real path of an existing file.

  • toFile() − Returns a File object representing this path.

  • normalize() − Returns a path that is this path with redundant name elements eliminated.

  • compareTo(Path other) − Compares two abstract paths lexicographically.This method returns zero if the argument is equal to this path, a value less than zero if this path is lexicographically less than the argument, or a value greater than zero if this path is lexicographically greater than the argument.

  • endsWith(Path other) − Tests if this path ends with the given path.If the given path has N elements, and no root component, and this path has N or more elements, then this path ends with the given path if the last N elements of each path, starting at the element farthest from the root, are equal.

  • endsWith(String other) − Tests if this path ends with a Path, constructed by converting the given path string, in exactly the manner specified by the endsWith(Path) method.

Example

Following example illustartes the different methods of Path interface which are mentioned above −

package com.java.nio;
import java.io.IOException;
import java.nio.Buffer;
import java.nio.ByteBuffer;
import java.nio.file.FileSystem;
import java.nio.file.LinkOption;
import java.nio.file.Path;
import java.nio.file.Paths;
public class PathDemo {
   public static void main(String[] args) throws IOException {
      Path path = Paths.get("D:/workspace/ContentW/Saurav_CV.docx");
      FileSystem fs =  path.getFileSystem();
      System.out.println(fs.toString());
      System.out.println(path.isAbsolute());
      System.out.println(path.getFileName());
      System.out.println(path.toAbsolutePath().toString());
      System.out.println(path.getRoot());
      System.out.println(path.getParent());
      System.out.println(path.getNameCount());
      System.out.println(path.getName(0));
      System.out.println(path.subpath(0, 2));
      System.out.println(path.toString());
      System.out.println(path.getNameCount());
      Path realPath = path.toRealPath(LinkOption.NOFOLLOW_LINKS);
      System.out.println(realPath.toString());
      String originalPath = "d:\\data\\projects\\a-project\\..\\another-project";
      Path path1 = Paths.get(originalPath);
      Path path2 = path1.normalize();
      System.out.println("path2 = " + path2);
   }
}
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