Delete files with certain extension only using FilenameFilter in Java

Byron KiourtzoglouFebruary 17th, 2013Last Updated: February 17th, 2013

0 116 1 minute read

In this tutorial we are going to show you how to use the FilenameFilter interface in Java in order to list all the file with a certain property in their names. In this example for instance, we want to delete all the text files in a specific directory, hence the files ending with “.txt” extension. Instances of classes that implement this interface are used to filter filenames. These instances are used to filter directory listings in the list method of class File.

In short to delete files with certain extensions using FilenameFilter you have to:

Create a class that implements the FilenameFilter interface and override the accept method to perform the filtering you want in the filename.
Use the above class as the argument in the list method, when listing the files of the target directory.

So here is the FileFilter class the implements FilenameFilter interface:

FileFilter.java

package com.javacodegeeks.java.core;

import java.io.File;
import java.io.FilenameFilter;

public class FileFilter implements FilenameFilter {

	private String fileExtension;

	public FileFilter(String fileExtension) {
		this.fileExtension = fileExtension;
	}

	@Override
	public boolean accept(File directory, String fileName) {
		return (fileName.endsWith(this.fileExtension));
	}
}

DeleteTextFiles.java

package com.javacodegeeks.java.core;

import java.io.File;

public class DeleteTextFiles {

	private static String parentDirectory = "C:\\Users\\nikos7\\Desktop\\files";
	private static String deleteExtension = ".txt";

	public static void main(String[] args) {
		FileFilter fileFilter = new FileFilter(deleteExtension);
		File parentDir = new File(parentDirectory);

		// Put the names of all files ending with .txt in a String array
		String[] listOfTextFiles = parentDir.list(fileFilter);

		if (listOfTextFiles.length == 0) {
			System.out.println("There are no text files in this direcotry!");
			return;
		}

		File fileToDelete;

		for (String file : listOfTextFiles) {

			//construct the absolute file paths...
			String absoluteFilePath = new StringBuffer(parentDirectory).append(File.separator).append(file).toString();

			//open the files using the absolute file path, and then delete them...
			fileToDelete = new File(absoluteFilePath);
			boolean isdeleted = fileToDelete.delete();
			System.out.println("File : " + absoluteFilePath + " was deleted : " + isdeleted);
		}
	}
}

Output:

File : C:\Users\nikos7\Desktop\files\file1.txt was deleted : true
File : C:\Users\nikos7\Desktop\files\file2.txt was deleted : true
File : C:\Users\nikos7\Desktop\files\file3.txt was deleted : true
File : C:\Users\nikos7\Desktop\files\file4.txt was deleted : true
File : C:\Users\nikos7\Desktop\files\file5.txt was deleted : true

This was an example on how to delete files with certain extension only using FilenameFilter in Java.