Thursday, October 28, 2010

Display Extension

This program reads in a file name and displays the extension (that last part of the name after the final dot).

import javax.swing.*;

public class FileExt {

public static void main(String[] args) {
//... Declare local variables.
String fileName; // The file name the user entered.
String extension; // The extension.

//... Input a file name and remove whitespace.
fileName = JOptionPane.showInputDialog(null, "Enter file name.");
fileName = fileName.trim();

//... Find the position of the last dot. Get extension.
int dotPos = fileName.lastIndexOf(".");
extension = fileName.substring(dotPos);

//... Output extension.
JOptionPane.showMessageDialog(null, "Extension is " + extension);

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