Simple Encrypter and Decrypter Class

I am posting a simple Enc and Dec class, which i was googling for a
long time but didnt find.

Hope this will help some one.

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

public class EncrypterDecrypter
{

    private static final String UNICODE_FORMAT = "UTF8";

    public String encrypt( String unencryptedString ) throws
EncryptionException
    {
        if ( unencryptedString == null || unencryptedString.trim().length()
== 0 )
                throw new IllegalArgumentException(
                        "Unencrypted string cant be null or empty" );

        try
        {
            byte[] keyAsBytes = unencryptedString.getBytes( UNICODE_FORMAT );
            BASE64Encoder base64encoder = new BASE64Encoder();
            return base64encoder.encode( keyAsBytes );
        }
        catch (Exception e)
        {
            throw new EncryptionException( e );
        }
    }

    public String decrypt( String encryptedString ) throws
EncryptionException
    {
        if ( encryptedString == null || encryptedString.trim().length() <=
0 )
                throw new IllegalArgumentException( "Encrypted string cant be null
or empty" );

        try
        {

            BASE64Decoder base64decoder = new BASE64Decoder();

            byte[] uncr = base64decoder.decodeBuffer( encryptedString );

            return toStr( uncr );
        }
        catch (Exception e)
        {
            throw new EncryptionException( e );
        }
    }

    private static String toStr( byte[] bytes )
    {
        StringBuffer stringBuffer = new StringBuffer();
        for (int i = 0; i < bytes.length; i++)
        {
            stringBuffer.append( (char) bytes[i] );
        }
        return stringBuffer.toString();
    }

    public static class EncryptionException extends Exception
    {
        public EncryptionException( Throwable t )
        {
            super( t );
        }
    }

    public static void main (String s[]) throws Exception
    {
        EncrypterDecrypter ed = new EncrypterDecrypter();

        if (s.length != 2)
        {
            log(" Not enough parameters ");
            log(" Usage : \n java EncrypterDecrypter 1 <string> \n \t or \n
java EncrypterDecrypter 2 <string> \n \t 1 -> Encryption 2->
Decryption");
            System.exit(0);
        }

        int action = -1;
        String str = null;

        try
        {
            action = Integer.parseInt(s[0]);
        }
        catch(Exception e)
        {
            log (" Invalid input provided for first param");
            System.exit(0);
        }

        log(" Action to be taken :"+ action);

        switch(action)
        {
            case 1:
                    String encr = ed.encrypt(s[1]);
                    log(" Encrypted String "+ s[0]+" is : "+ encr);
                    break;

            case 2:
                    String decr = ed.decrypt(s[1]);
                    log(" Decrypted String of "+ s[1]+" is : "+ decr);
                    break;

            case 9:
                    String enc = ed.encrypt(s[1]);
                    log(" Encrypted String : "+ enc);
                    String dec = ed.decrypt(enc);
                    log(" Decrypted String : "+ dec);
                    break;

            default:
                    log(" Wrong parameter value passed, please check ... ");
                    break;

        }

    }

    public static void log(String s)
    {
        System.out.println(s);
    }
}