Java file extension

In this section you will learn how to display the file extension of the file.

Description of code:

Files are usually known through their extensions. An extension differentiates the file from another file. It recognizes the file type. To find the extension from its file is a common task.

You can see in the give example, we have created an object of class File and specify a text file as an argument. The method getName() returns the name of the file. Then we have used substring() method to return a new string consists of file extension.

Here is the code:

import java.io.*;

public class FileExtension {
	public static void main(String[] args) {
		File file = new File("C:/file.txt");
		String fname = file.getName();
		String ext = fname
				.substring(fname.lastIndexOf('.') + 1, fname.length());
		System.out.println("Extension of file " + fname + " is: " + ext);
	}
}

Through the above code, you can determine the extension of any file.

Output:

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