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How to Get File Extension in Java
Ramesh Fadatare edited this page Jul 18, 2018
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In this example, we will check the file extensions such as txt, docx,pdf etc.
- Let's use lastIndexOf() method of String class to find the index of last character ".".
- First check whether the file has extention or not.
- Use substring() method to get extension of the file.
package com.javaguides.javaio.fileoperations.fileexamples; import java.io.File; /** * This Java program demonstrates how to get file extension in Java example. * @author javaguides.net */ public class GetFileExtensionExample { private static String getFileExtension(File file) { String fileName = file.getName(); if (fileName.lastIndexOf('.') != -1 && fileName.lastIndexOf('.') != 0) { return fileName.substring(fileName.lastIndexOf('.') + 1); } else { return "File don't have extension"; } } public static void main(String[] args) { File file = new File("sample.txt"); System.out.println(getFileExtension(file)); File file1 = new File("sample"); System.out.println(getFileExtension(file1)); File file2 = new File("sample.docx"); System.out.println(getFileExtension(file2)); } }
Output of the above program is:
txt
File don't have extension
docx
https://docs.oracle.com/javase/8/docs/api/java/io/File.html https://docs.oracle.com/javase/8/docs/api/java/lang/String.html