Create A Login Form Using NetBeans IDE

How to create a login form(Java GUI Programming) through NetBeans IDE or how to use JPassword?

We will be using a text field to get the username and a password field to get the password.

1st Method
STEP-1 First of all design your form by placing the required components i.e label, text-field, password field and a button to perform the action.

Here, I have used a panel with titled border to make design look better.

STEP-2 Double-click on the ‘Log In’ button or right click»Events»Action»actionPerformed

STEP-3 On the Log In button’s action performed event, write the following piece of code

String user=jTextField1.getText();

String pwd= new String (jPasswordField1.getPassword());

if (user.equals(“yourusername“) && pwd.equals(“yourpassword“))

       new Home().setVisible(true);

Explanation of code- We will accept the password from the password field and store it in the variable pwd. Similarly, we will store the username in the variable user. Now, we can compare the username and password we have received to the real username and password using the if command.
Now if the username and password is correct your Home page(Java form) could be visible or you can perform any other action.

If there is only few IDs i.e only few combinations of username and password you can use If-else-if but if the IDs are more in number you have to maintain a database of usernames and their corresponding password. In such a case you can use a DBMS eg- MySQL. After that you have to create a connection between your database and your Java application.

2nd Method (Using Java Database Connectivity)

STEP-1 Same as above.

STEP-2 Add ‘MySql JDBC Driver’ Library in your project(Right click on project icon » Properties » Libraries » Add Library » MySql JDBC Driver)

STEP-3 Under your package and before class starts write the following codes in the source tab.

import java.sql.*;

import javax.swing.JOptionPane;

STEP-3 Now on the Login button’s actionPerformed event

String sql=”Select * from Table_name“;

try {

Class.forName(“com.mysql.jdbc.Driver”);

Connection con= (Connection) DriverManager.getConnection(“jdbc:mysql://localhost:3306/yourdatabasename“,”yourmysqlid“,”yourmysqlpassword“);

/*As we are creating a connection on a local computer we will write the url as jdbc:mysql://localhost:3306 */

Statement stmt=con.createStatement();

ResultSet rs = stmt.executeQuery(sql);
}
catch (Exception e){
JOptionPane.showMessageDialog(this, e.getMessage());
}

STEP-4 Now we have to match our inputs of username and password with that in the database. We will use while loop for this purpose. Write the following codes under the line ResultSet rs = stmt.executeQuery(sql); and before the ‘}‘

String user=jTextField1.getText();
String pwd= new String (jPasswordField1.getPassword());
while(rs.next()) {
String uname=rs.getString(“Username“);
//Username is the coloumn name in the database table
String password=rs.getString(“Password“);
if ((user.equals(uname)) && (pwd.equals(password)))
new Home().setVisible(true);
}

The loop will execute the number of times equal to the total of rows in the table. The Home form will open when the right combination of username and password is found.

Tips regarding Log In form

1) There are always chances that a user will enter a wrong password and username combination, in that case you should show a  message to the user regarding the same. You can use a JOptionPane for this purpose.
a- For 1st Method
You can put a else statement for displaying this error message.

else {
JOptionPane.showMessageDialog(this, “Incorrect Username or Password!”);
}

b- For 2nd Method
There maybe other methods but I thought this one to be the simplest one.
Before the while loop starts declare a integer variable and initialize it with the value 0 and later in the loop we can increase its value if a right match is found. Here’s the complete code that I used.

int tmp=0;
while(rs.next()) {
String uname=rs.getString(“Username“);
String password=rs.getString(“Password“);
if ((user.equals(uname)) && (pwd.equals(password))) {
new Home().setVisible(true);
tmp++;
    }
}
if (tmp==0) {
JOptionPane.showMessageDialog(null, “Username and Password not in database!”);
   }

2) If you are opening a new form after a login is successful, there will be two forms on the screen as the login form will not close. So to close the login form just write dispose(); below the line new Home().setVisible(true); This will close the current form(i.e login) and there will be only one form on the screen.

3) Important properties for Password field.

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