doing some school coursework and currently creating a basic login system that will store usernames and passwords in a text file. I am new to java and found an old tutorial on making a similar system. everything works so far including the program being able to fetch the username from the input but any time i try the password as well i ge a whole host of errors. I have searched for the best part of half an hour and cant seem to find relevant information so was just wondering if anyone could help or link me to a post or website that covers what i need (for context i am currently trying to get it to pring the username and password to the terminal just to test that it can fetch them properly)
code:
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.JPanel;
import javax.swing.JPasswordField;
import javax.swing.JTextField;
public class GUI implements ActionListener {
private static JLabel userLabel;
private static JTextField userText;
private static JLabel passwordLabel;
private static JPasswordField passwordText;
private static JButton button;
private static JLabel success;
public static void main(String[] args) {
JFrame frame = new JFrame();
JPanel panel = new JPanel();
frame.setSize(400, 200);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(panel);
panel.setLayout(null);
userLabel = new JLabel("User");
userLabel.setBounds(10, 20, 80, 25);
panel.add(userLabel);
userText = new JTextField(20);
userText.setBounds(100, 20, 165 ,25);
panel.add(userText);
passwordLabel = new JLabel("Password");
passwordLabel.setBounds(10, 50, 80, 25);
panel.add(passwordLabel);
JPasswordField passwordText = new JPasswordField();
passwordText.setBounds(100, 50, 165, 25);
panel.add(passwordText);
button = new JButton("Login");
button.setBounds(10, 80, 80, 25);
button.addActionListener(new GUI());
panel.add(button);
success = new JLabel("");
success.setBounds(10, 110, 300, 25);
panel.add(success);
frame.setVisible(true);
}
@Override
public void actionPerformed(ActionEvent e) {
String user = userText.getText();
String passwordString = String.valueOf(passwordText.getPassword());
System.out.println(user + ", " + passwordString);
System.out.println(user);
}
}
error (after clicking the button):
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException: Cannot invoke "javax.swing.JPasswordField.getPassword()" because "GUI.passwordText" is null
at GUI.actionPerformed(GUI.java:57)
at java.desktop/javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1967)
at java.desktop/javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2308)
at java.desktop/javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:405)
at java.desktop/javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:262)
at java.desktop/javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:279)
at java.desktop/java.awt.Component.processMouseEvent(Component.java:6614)
at java.desktop/javax.swing.JComponent.processMouseEvent(JComponent.java:3342)
at java.desktop/java.awt.Component.processEvent(Component.java:6379)
at java.desktop/java.awt.Container.processEvent(Container.java:2263)
at java.desktop/java.awt.Component.dispatchEventImpl(Component.java:4990)
at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2321)
at java.desktop/java.awt.Component.dispatchEvent(Component.java:4822)
at java.desktop/java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4919)
at java.desktop/java.awt.LightweightDispatcher.processMouseEvent(Container.java:4548)
at java.desktop/java.awt.LightweightDispatcher.dispatchEvent(Container.java:4489)
at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2307)
at java.desktop/java.awt.Window.dispatchEventImpl(Window.java:2769)
at java.desktop/java.awt.Component.dispatchEvent(Component.java:4822)
at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:772)
at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:721)
at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:715)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:391)
at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85)
at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:95)
at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:745)
at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:743)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:391)
at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85)
at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:742)
at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)
JPasswordField passwordText = new JPasswordField();
passwordText.setBounds(100, 50, 165, 25);
panel.add(passwordText);
You're re-declaring passwordText. That way you're obscuring the passwordText class variable, and never initializing it, so when you refer to it in your actionPerformed method a NullPointerException is thrown.
Just remove the re-declaration, i.e.
passwordText = new JPasswordField();
passwordText.setBounds(100, 50, 165, 25);
panel.add(passwordText);