Problemas com criptografia padrão MD5

package util;

import java.security.*;

public class MD5 {
    
/*  RFC1321 MD5: http://www.faqs.org/rfcs/rfc1321.html
 
    MD5 test suite:
    MD5 ("") = d41d8cd98f00b204e9800998ecf8427e
    MD5 ("a") = 0cc175b9c0f1b6a831c399e269772661
    MD5 ("abc") = 900150983cd24fb0d6963f7d28e17f72
    MD5 ("message digest") = f96b697d7cb7938d525a2f31aaf161d0
    MD5 ("abcdefghijklmnopqrstuvwxyz") = c3fcd3d76192e4007dfb496cca67e13b
    MD5 ("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789") =
    d174ab98d277d9f5a5611c2c9f419d9f
    MD5 ("12345678901234567890123456789012345678901234567890123456789012345678901234567890") = 57edf4a22be3c955ac49da2e2107b67a
 */
    
    private static String hexDigits = "0123456789abcdef";
    private static MessageDigest md = null;
    
    
    /**
     * Calculates the MD5 hash of str using the
     *    RSA Data Security, Inc. MD5 Message-Digest Algorithm,
     * @return String containing 32 hexadecimal hash or null in case of error.
     */
    public static String md5(String str){
        try{
            if (md == null){
                md = MessageDigest.getInstance("MD5");
            }
            
            byte b[];
            StringBuffer sbuffer = new StringBuffer();
            md.reset();
            b = md.digest( str.getBytes() );
            for (int i = 0; i < 16; i++) {
                int j = ((int) b[i]) & 0xFF;
                sbuffer.append(hexDigits.charAt(j / 16));
                sbuffer.append(hexDigits.charAt(j % 16));
            }
            return sbuffer.toString();
        }
        catch(Exception e){
            System.err.println("Error MD5: "+e.getMessage());
        }
        
        return null;
    }
    
}

all:
        [echo] Rodando aplicacao
        //Gero a senha
        [java] "MESTRE" criptografado eh: 55cc1e315cbf9dab702675ff92c7fb35
        //gravo no banco
        [java] Dados inseridos com sucesso.
        //recupero a senha no banco
        [java] Senha cadastrada no banco para o login "ANJOMAL" foi: 55cc1e315cbf9dab702675ff92c7fb35
        //comparo a senha que está gravada no banco com MD5Builder.md5("MESTRE");
        [java] Comparando as senhas...
        [java] Senha bateu
        [echo] Pronto!

stmt = con.prepareStatement("select * from users where login = ?");
    stmt.setString(1, "ANJOMAL");
    ResultSet rs = stmt.executeQuery();
    String senhaNoBanco = null;
  
    if (rs.next()) {
      senhaNoBanco = rs.getString("senha");
    } else {
      throw new RuntimeException("Usuário "ANJOMAL" não encontrado");
    }

    System.out.println("Senha cadastrada no banco para o login "ANJOMAL" " +
        "foi: " + senhaNoBanco);
        
    System.out.println("Comparando as senhas...");
    
    //Renomeei tua classe de MD5 para MD5Builder
    if (MD5Builder.md5("MESTRE").equalsIgnoreCase(senhaNoBanco)) {
      System.out.println("Senha bateu");
    } else {
      System.out.println("Login falhou");
    }

[java] "MESTRE" criptografado eh: 55cc1e315cbf9dab702675ff92c7fb35
        [java] "mestre" criptografado eh: 989b731fca676f41b6a48c6ccb0d4801
        [java] "MeStRe" criptografado eh: 36b310074e6890dd9db2b8437668cad8

char[] aChar = {'E', 'l', 'v', 'i', 's'};
    System.out.println(aChar.toString());
    String nome = new String(aChar);
    System.out.println(nome);
    System.out.println("Sacou?");
  }

[C@601bb1
Elvis
Sacou?