added a second password text field so the user has to input the same password twice

src/main/java/SignUpGUI.java

@@ -4,12 +4,12 @@ import java.awt.event.ActionListener;
 import java.util.UUID;
 
 public class SignUpGUI extends JFrame implements ActionListener {
-	private JTextField usernameField, passwordField, birthdayField;
+	private JTextField usernameField, passwordField, confirmPasswordField, birthdayField;
     private JButton signUpButton;
     
     public SignUpGUI() {
         setTitle("Sign Up");
-        setSize(300, 200);
+        setSize(300, 250);
         setDefaultCloseOperation(EXIT_ON_CLOSE);
         setLayout(null);
 
@@ -29,16 +29,24 @@ public class SignUpGUI extends JFrame implements ActionListener {
         passwordField.setBounds(100, 50, 160, 25);
         add(passwordField);
 
+        JLabel confirmPasswordLabel = new JLabel("Confirm Password:");
+        confirmPasswordLabel.setBounds(20, 80, 120, 25);
+        add(confirmPasswordLabel);
+
+        confirmPasswordField = new JPasswordField();
+        confirmPasswordField.setBounds(140, 80, 120, 25);
+        add(confirmPasswordField);
+
         JLabel birthdayLabel = new JLabel("Birthday:");
-        birthdayLabel.setBounds(20, 80, 80, 25);
+        birthdayLabel.setBounds(20, 110, 80, 25);
         add(birthdayLabel);
 
         birthdayField = new JTextField();
-        birthdayField.setBounds(100, 80, 160, 25);
+        birthdayField.setBounds(100, 110, 160, 25);
         add(birthdayField);
 
         signUpButton = new JButton("Sign Up");
-        signUpButton.setBounds(100, 120, 100, 25);
+        signUpButton.setBounds(100, 150, 100, 25);
         signUpButton.addActionListener(this);
         add(signUpButton);
 
@@ -49,8 +57,13 @@ public class SignUpGUI extends JFrame implements ActionListener {
     	if (e.getSource() == signUpButton) {
             String username = usernameField.getText();
             String password = passwordField.getText();
+            String confirmPassword = confirmPasswordField.getText();
             String birthday = birthdayField.getText();
 
+            if (!password.equals(confirmPassword)) {
+                JOptionPane.showMessageDialog(this, "Passwords do not match!", "Sign Up Error", JOptionPane.ERROR_MESSAGE);
+                return;
+            }
             try {
                 UUID randomUUID = UUID.randomUUID();
                 CreateUser user = CreateUser.createUser(randomUUID.toString(), username, password, birthday);

user.json

@@ -22,5 +22,11 @@
     "userName": "asd",
     "password": "asdasdasd",
     "birthday": "asd"
+  },
+  {
+    "id": "1e035bce-37b5-4f1e-894e-8136b8021c4d",
+    "userName": "asd",
+    "password": "123456",
+    "birthday": "1234"
   }
 ]