Default defective password validation method

DefaultDefectivePasswordValidator.java

public class DefaultDefectivePasswordValidator implements DefectivePasswordValidator {

    private static List<String> crackedPasswords = new ArrayList<>();
    private static DefaultDefectivePasswordValidator dPasswordValidator = new DefaultDefectivePasswordValidator();

    private static final Logger log = LoggerFactory.getLogger(DefaultDefectivePasswordValidator.class);

    private DefaultDefectivePasswordValidator() {
    }

    public static DefaultDefectivePasswordValidator getInstance() {
        return dPasswordValidator;
    }

    /**
     * initialize defective password values from the given text file
     */
    @Override
    public void initValues() {
        crackedPasswords = new ArrayList<>();
        try {
            crackedPasswords = Files.readAllLines(Paths.get(DefectivePasswordValidatorConstants.PASSWORD_FILE_PATH),
                    StandardCharsets.UTF_8);
        } catch (IOException e) {
            log.error("Exception occured while reading and initializing values from "
                    + DefectivePasswordValidatorConstants.PASSWORD_FILE_NAME, e);
        }
    }

    /**
     * validate method
     */
    @Override
    public boolean validate(Object credential) {
        return !crackedPasswords.contains((String) credential);
    }
}