java.nio.file.SimpleFileVisitor Class in Java

The java.nio.file.SimpleFileVisitor Class is used to visit all the files in a directory and to re-throw I/O exceptions whenever an I/O error occurs.

Class declaration :

public class SimpleFileVisitor<T>
extends Object
implements FileVisitor<T>

Constructor:

• protected SimpleFileVIsitor(): Creates a new object of SimpleFileVisitor class.

Method:

Method	Description
public FileVisitResult preVisitDirectory(T directory, BasicFileAttributes attributes)	This method is invoked for this directory before the entries are visited. This method returns to CONTINUE unless overridden.
public FileVisitResult postVisitDirectory(T directory, IOException e)	This method is invoked for this directory after the entries are visited. This method returns to CONTINUE unless overridden.
public FileVisitResult visitFile(T file, BasicFileAttributes attributes)	This method is invoked for this file before in a directory. This method returns to CONTINUE unless overridden.
public FileVisitResult visitFileFailed(T file, IOException exception)	This method is invoked for a file that could not be visited. This method re-throws the I/O exception unless overridden. This was the exception that prevented the file from being visited.

1.public FileVisitResult preVisitDirectory(T directory, BasicFileAttributes attributes): This method is invoked for this directory before the entries in the are visited. This method returns to CONTINUE unless overridden.

Parameters:
directory- reference to this directory.
attributes- attributes of this directory.

Returns: the file visit result.

Throws: I/O Exception.

2.public FileVisitResult postVisitDirectory(T directory, IOException e): This method is invoked for this directory after the entries in the are visited. This method returns to CONTINUE unless overridden.

Parameters:
directory- reference to this directory.
e- NULL if there is no error in this directory's 
iteration,else the I/O exception.

Returns: the file visit result.

Throws: I/O Exception.

3.public FileVisitResult visitFile(T file, BasicFileAttributes attributes): This method is invoked for this file before in a directory. This method returns to CONTINUE unless overridden.

Parameters:
file- reference to this file.
attributes- attributes of this file.

Returns: the file visit result.

Throws: I/O Exception 

4.public FileVisitResult visitFileFailed(T file, IOException exception): This method is invoked for a file that could not be visited. This method re-throws the I/O exception unless overridden. This was the exception that prevented the file from being visited.

Parameters:
file - reference to this file.
exc - exception that prevented the file from being visited.

Returns: the file visit result.

Throws: I/O Exception 

Java

// Java program to demonstrate working of simpleFileVisitor
// class

import java.io.IOException;
import java.nio.file.*;
import java.nio.file.attribute.*;

public class FileVisitorDemo
    extends SimpleFileVisitor<Path> {
    public FileVisitResult
    visitFile(Path file, BasicFileAttributes atts)
        throws IOException
    {
        if (file.getFileName().toString().endsWith(
                ".txt")) { // delete files ending with .txt
            Files.delete(file);
        } // return result of the operation
        return FileVisitResult.CONTINUE;
    }
    // Method to print message if file visit was not
    // successful
    public FileVisitResult visitFileFailed(Path file,
                                           IOException e)
        throws IOException
    {
        System.err.println("File could not be visited");
        return FileVisitResult.CONTINUE;
    }
    public static void main(String args[]) throws Exception
    {
        FileVisitorDemo visitor = new FileVisitorDemo();
        try {
            // visiting all files at
            // "/Users/abhinavjain194/desktop/visit"
            Files.walkFileTree(
                Paths.get(
                    "/Users/abhinavjain194/desktop/visit"),
                visitor);
        }
        catch (Exception e) { // printing error if occurred
            System.err.print(e.toString());
        }
    }
}

Before running the program

After running the program