Get file extension name in Java

Java 8Object Oriented ProgrammingProgramming

The file extension is the suffix that is attached to the computer file and it denotes the format of the file. A program that demonstrates getting the file extension name is given as follows −

Example

 Live Demo

import java.io.File;
public class Demo {
   private static String fileExtension(File file) {
      String name = file.getName();
      if(name.lastIndexOf(".") != -1 && name.lastIndexOf(".") != 0)
         return name.substring(name.lastIndexOf(".") + 1);
      else
         return "";
   }
   public static void main(String[] args) {
      File file = new File("demo1.txt");
      System.out.println("The file extension is: " + fileExtension(file));
   }
}

The output of the above program is as follows −

Output

The file extension is: txt

Now let us understand the above program.

The method fileExtension() returns the file extension and it takes a single parameter i.e. the File class object. A code snippet that demonstrates this is given as follows −

private static String fileExtension(File file) {
   String name = file.getName();
   if(name.lastIndexOf(".") != -1 && name.lastIndexOf(".") != 0)
      return name.substring(name.lastIndexOf(".") + 1);
   else
      return "";
}

The method main() calls the method fileExtension() and prints the file extension returned. A code snippet that demonstrates this is given as follows −

public static void main(String[] args) {
   File file = new File("demo1.txt");
   System.out.println("The file extension is: " + fileExtension(file));
}
raja
Published on 25-Feb-2019 11:45:42
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