[Java] Créer une excpetion

throw new MauvaisFormatException(MauvaisFormatException.BAD_FILE_FORMAT);

import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;

/*
 * Created on Jul 25, 2005
 *
 */

/**
 * @author Philippe Fery
 *
 */
public class ExceptionDemo {

	public ExceptionDemo() {
		super();
	}

	public void openfile(String filePath) throws MauvaisFormatException, FileNotFoundException, IOException {
		File file = new File(filePath);
		int lineCounter = 0;
		if (file.getName().endsWith(".txt") || file.getName().endsWith(".log")) {
			BufferedReader reader = new BufferedReader(new FileReader(file));
			String line = "";
			while ((line = reader.readLine()) != null) {
				lineCounter++;
				if (line.startsWith("DATA#")) {} else {
					throw new MauvaisFormatException(MauvaisFormatException.BAD_FILE_FORMAT);
				}
			}
			if (lineCounter < 100) {
				throw new MauvaisFormatException(MauvaisFormatException.BAD_FILE_EXTENSION);
			}
		} else {
			throw new MauvaisFormatException(MauvaisFormatException.BAD_FILE_LENGTH);
		}

	}

	class MauvaisFormatException extends Exception {
		public static final String BAD_FILE_EXTENSION = "Extension de fichier non valide";
		public static final String BAD_FILE_FORMAT = "Mauvais format de fichier";
		public static final String BAD_FILE_LENGTH = "Mauvaise taille de fichier";
		public String message;

		public MauvaisFormatException() {
			super();
			this.message = BAD_FILE_FORMAT;
		}

		public MauvaisFormatException(String message) {
			super(message);
			this.message = message;
		}

		public String getMessage() {
			return message;
		}
	}

	public static void main(String[] args) {
		ExceptionDemo demo = new ExceptionDemo();
		try {
			demo.openfile("c:/dir.txt");
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (MauvaisFormatException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}