Xevuel BMPNG convert

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

public class Xevuel {
    public static void main(String args[]) {
        if (args.length == 0) {
            System.err.println("ERR: No file specified");
            System.exit(-1);
        }
        if (!args[0].toLowerCase().endsWith(".bmp")) {
            System.err.println("ERR: Filename doesn't end with .bmp");
            System.exit(-1);
        }

        try {
            BufferedImage img = ImageIO.read(new File(args[0]));
            ImageIO.write(img, "png", new File(args[0].substring(0, args[0].length()-4) + ".png"));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}