Selenium Input Data
selenium.type("id=username","myName");
selenium.type("id=password","myPassword");
selenium.click("id=login");

public class EUAUser {

  private String username;
  private String password;
  private boolean isUsed

  public EUAUser(String uname, String pwd){
    this.username = uname;
    this.password = pwd;
    isUsed = false;
  }

   public String getPassword(){
    return password;
   }

 public String getUsername(){
    return username;
 }

 public void lockUser(){
     isUsed = true;
 }
}

public class UserPool {
private List<EUAUser> userList = new ArrayList<EUAUser>();

public UserPool(){

          userList.add(new EUAUser("firstUser","a"));
          userList.add(new EUAUser("MyUsername", "a"));
          userList.add(new EUAUser("TestUser", "a"));
          userList.add(new EUAUser("TSTUser2", "a"));

       }

  public EUAUser getNextUser() throws RuntimeException {
    for(EUAUser user: userList){
          if (!user.isUsed()){
              user.lockUser();
              return user;
      }
    }
    throw new RuntimeException("No free user found.");
}

UserPool pool = new UserPool();
 EUAUser user = pool.getNextUser();
 selenium.type("id=username", user.getUserName());
 selenium.type("id=password", user.getPassword());
 selenium.click("id=login");