package com.mvc.view;

import java.awt.Color;
import java.awt.Container;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPasswordField;
import javax.swing.JTextField;
import javax.swing.SwingConstants;

import com.mvc.controller.LoginController;

public class LoginView extends JFrame {

private static final long serialVersionUID = 3566038652320101414L;
private JTextField txtUsername;
private JPasswordField txtPassword;
private JButton btnLogin;
private JLabel lblErrorMessage;

public LoginView() {
    setTitle("MedIT: Login");
    setResizable(false);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(100, 100, 400, 250);
    Container contentPane = this.getContentPane();
    contentPane.setLayout(null);

    JLabel lblUsername = new JLabel("Username:");
    lblUsername.setFont(new Font("Tahoma", Font.BOLD, 14));
    lblUsername.setHorizontalAlignment(SwingConstants.RIGHT);
    lblUsername.setBounds(10, 11, 120, 25);
    contentPane.add(lblUsername);

    txtUsername = new JTextField();
    txtUsername.setFont(new Font("Tahoma", Font.PLAIN, 14));
    txtUsername.setBounds(140, 11, 200, 25);
    contentPane.add(txtUsername);

    JLabel lblPassword = new JLabel("Password:");
    lblPassword.setHorizontalAlignment(SwingConstants.RIGHT);
    lblPassword.setFont(new Font("Tahoma", Font.BOLD, 14));
    lblPassword.setBounds(10, 52, 120, 25);
    contentPane.add(lblPassword);

    txtPassword = new JPasswordField();
    txtPassword.setFont(new Font("Tahoma", Font.PLAIN, 14));
    txtPassword.setBounds(140, 52, 200, 25);
    contentPane.add(txtPassword);

    LoginController controller = new LoginController(this);
    btnLogin = new JButton("Login");
    btnLogin.addActionListener(new ActionListener(){
        @Override
        public void actionPerformed(ActionEvent arg0) {
            controller.checkCredentials(txtUsername.getText(), new String(txtPassword.getPassword()));
        }
    });
    btnLogin.setFont(new Font("Tahoma", Font.PLAIN, 14));
    btnLogin.setBounds(251, 93, 89, 25);
    contentPane.add(btnLogin);

    lblErrorMessage = new JLabel("");
    lblErrorMessage.setHorizontalAlignment(SwingConstants.RIGHT);
    lblErrorMessage.setForeground(Color.RED);
    lblErrorMessage.setFont(new Font("Tahoma", Font.PLAIN, 14));
    lblErrorMessage.setBounds(10, 151, 330, 25);
    contentPane.add(lblErrorMessage);
}

public void setErrorMessage(String errorMessage) {
    lblErrorMessage.setText(errorMessage);
}

public static void main(String args[]){
    LoginView view = new LoginView();
    view.setVisible(true);
}
}

package com.mvc.controller;

import com.mvc.model.LoginModel;
import com.mvc.view.LoginView;

public class LoginController {

private LoginView view;
private LoginModel model;

public LoginController(LoginView view){
    this.view = view;
    model = new LoginModel();
}

public void checkCredentials(String username, String password){
    model.setUsername(username);
    model.getCredentials();
    if(password.equals(model.getPassword())){
        view.setErrorMessage("Login Success!");
    }
    else{
        view.setErrorMessage("Login Failed!");
    }
}
}

package com.mvc.model;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class LoginModel {
private String username, password;
private Connection conn;

public void setUsername(String username) {
    this.username = username;
}

public String getPassword() {
    return password;
}

public void setPassword(String password) {
    this.password = password;
}

public void getCredentials(){
    try {
        Class.forName("org.apache.derby.jdbc.EmbeddedDriver");
        conn = DriverManager.getConnection("jdbc:derby:db/medit");
        PreparedStatement select = conn.prepareStatement("SELECT * FROM user_credentials WHERE username = ?");
        select.setString(1, username);
        ResultSet rs = select.executeQuery();
        if(rs.next()){
            password = rs.getString("password");
        }
        else{
            password = "";
        }
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    }catch (SQLException e) {
        e.printStackTrace();
    }
    finally{
        try {
            conn.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}
}