Java

import java.util.Scanner;
import javax.swing.JOptionPane;
import javax.swing.*;
    public class Wewe{
        public static void main(String[]args){
            Scanner inp = new Scanner(System.in);
            boolean tryAgain;
            do{
            System.out.print("\nInput username: ");
            String user = inp.nextLine();
            System.out.print("\nInput password: ");
            String pass = inp.nextLine();
        if(user.equals("admin") && pass.equals("admin")){
                System.out.print("Success!");
                tryAgain = true;
            }
            if(user!="admin" && pass!="admin"){
                JOptionPane.showMessageDialog(null, "Try again! Invalid username or password!","Error Logging-In", JOptionPane.ERROR_MESSAGE);
            tryAgain = false;
        }
    }while(tryAgain = true);
            }
        }