To Find the Extension of Given File Using JOptionPane Dialog Box

Here is a Java Program to Find the Extension of Given File Using JOptionPane Dialog Box

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import javax.swing.*;   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);     } }

Output of Above Java Program