Passay libary provides a MessageResolver API to override the default messages used by the validator. It can take the path to custom properties file and use the standard keys to override the required message.

Example

The below example shows the validation of a password and show a custom message using Passay library.

messages.properties

INSUFFICIENT_UPPERCASE=Password missing at least %1$s uppercase characters.

PassayExample.java

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import java.util.Properties;

import org.passay.CharacterRule;
import org.passay.EnglishCharacterData;
import org.passay.LengthRule;
import org.passay.MessageResolver;
import org.passay.PasswordData;
import org.passay.PasswordValidator;
import org.passay.PropertiesMessageResolver;
import org.passay.Rule;
import org.passay.RuleResult;
import org.passay.WhitespaceRule;

public class PassayExample {
   public static void main(String[] args) throws FileNotFoundException, IOException {
      List<Rule> rules = new ArrayList<>();
      rules.add(new LengthRule(8, 16));
      rules.add(new WhitespaceRule());
      rules.add(new CharacterRule(EnglishCharacterData.UpperCase, 1));
      rules.add(new CharacterRule(EnglishCharacterData.LowerCase, 1));
      rules.add(new CharacterRule(EnglishCharacterData.Digit, 1));
      rules.add(new CharacterRule(EnglishCharacterData.Special, 1));

      Properties props = new Properties();
      props.load(new FileInputStream("E:/Test/messages.properties"));
      MessageResolver resolver = new PropertiesMessageResolver(props);

      PasswordValidator validator = new PasswordValidator(resolver, rules);
      PasswordData password = new PasswordData("microsoft@123");
      RuleResult result = validator.validate(password);
      if(result.isValid()){
         System.out.println("Password validated.");
      }else{
         System.out.println("Invalid Password: " + validator.getMessages(result));            
      }
   }
}

Output

Invalid Password: [Password missing at least 1 uppercase characters.]