Here is an Custom Realm Authendication Program for a single user help me out with multiple users

The below code is a Tomcat Custom Realm Authentication code where if user gives password as "test" it logs in successfully

how can i modify this program such that if i have 5 user and each with different password stored in an array

and also tell me the way of execution of this realm which fuction is executed first and who calls these functions

import java.security.Principal;
import java.util.ArrayList;
import java.util.List;
import org.apache.catalina.realm.RealmBase;
import org.apache.catalina.realm.GenericPrincipal;

 public class NewRealm extends RealmBase 
   {
     private String username;
     private String password;
     @Override
     public Principal authenticate(String username, String credentials) 
        {
          this.username = username;
          this.password = credentials;
          if (this.username.equals(this.password)) 
           {
            return getPrincipal(username);
           }
            else
            {
            return null;
            }
          }
         @Override
         protected String getName() {
         return username;
          }
         @Override
         protected String getPassword(String username) {
         return "test";
         }
         @Override
         protected Principal getPrincipal(String string) {
         List<String> roles = new ArrayList<String>();
         roles.add("user");
       Principal principal = new GenericPrincipal(username,"test",roles);
       return principal;
     }
   }