JButton in JFrame does not work

Question

I'm currently working on a simple project in Netbeans, getting used to the JFrame Form. I created a couple of JFrames and I want to jump through them by pressing buttons, but whenever I press a button nothing happens.

This is my code

public class MainLogIn extends javax.swing.JFrame {

/**
 * Creates new form MainLogIn
 */

//testdata
private String[] dummy_data = {"user1:parola1", "user2:parola2"};

public MainLogIn() {
    initComponents();

    LogIn = new JButton();
    signUp = new JButton();
    username = new JTextField();
    password = new JPasswordField();

    wrong = new JLabel();
    wrong.setVisible(false);
}

/**
 * This method is called from within the constructor to initialize the form.
 * WARNING: Do NOT modify this code. The content of this method is always
 * regenerated by the Form Editor.
 */
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">                          
private void initComponents() {

    jLabel1 = new javax.swing.JLabel();
    jLabel2 = new javax.swing.JLabel();
    username = new javax.swing.JTextField();
    password = new javax.swing.JPasswordField();
    LogIn = new javax.swing.JButton();
    signUp = new javax.swing.JButton();
    wrong = new javax.swing.JLabel();

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

    jLabel1.setText("Username:");

    jLabel2.setText("Password:");

    LogIn.setText("LogIn");
    LogIn.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            LogInActionPerformed(evt);
        }
    });

    signUp.setText("SignUp");
    signUp.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            signUpActionPerformed(evt);
        }
    });

    wrong.setText("Wrong Username And Password");
    wrong.setVisible(false);

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(layout.createSequentialGroup()
                    .addGap(16, 16, 16)
                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                        .addComponent(jLabel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                        .addComponent(jLabel2, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
                    .addGap(31, 31, 31)
                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                        .addComponent(username, javax.swing.GroupLayout.DEFAULT_SIZE, 120, Short.MAX_VALUE)
                        .addComponent(password)))
                .addGroup(layout.createSequentialGroup()
                    .addGap(28, 28, 28)
                    .addComponent(LogIn)
                    .addGap(95, 95, 95)
                    .addComponent(signUp))
                .addGroup(layout.createSequentialGroup()
                    .addGap(60, 60, 60)
                    .addComponent(wrong)))
            .addContainerGap(146, Short.MAX_VALUE))
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addGap(51, 51, 51)
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                .addComponent(username, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 27, javax.swing.GroupLayout.PREFERRED_SIZE))
            .addGap(18, 18, 18)
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(jLabel2)
                .addComponent(password, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
            .addGap(52, 52, 52)
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(LogIn)
                .addComponent(signUp))
            .addGap(26, 26, 26)
            .addComponent(wrong)
            .addContainerGap(48, Short.MAX_VALUE))
    );

    pack();
}// </editor-fold>                        

private boolean isPasswordValid(String password)
{
    if(password.length()>8)
        return true;
    else
        return false;
}

private boolean loginAttempt(String user, String pass){

    String usertext, passtext;

    //get username and password
    usertext = user;
    passtext = pass;

    //check username
    if(usertext == null)
    {
        username.setText("Please add username");
    }
    if(passtext == null)
    {
        password.setText("Please add password");
    }
    else
        if(isPasswordValid(passtext) == false)
            password.setText("Password too short");

    //check for good data among dummy_data
    for(String credentials:dummy_data)
    {
        String[] user_pass = credentials.split(":");
        if(user_pass[0].equals(usertext) &&
           user_pass[1].equals(passtext))
            {
                return true;
            }
    }

    return false;
}


private void LogInActionPerformed(java.awt.event.ActionEvent evt) {                                      
    // TODO add your handling code here:
    String usertext, passtext;
    usertext = username.getText().toString();
    passtext = password.getText().toString();
    if(loginAttempt(usertext,passtext) == true)
    { 
        LogIn.addActionListener(new ActionListener()
        {
            @Override
            public void actionPerformed(ActionEvent ae) {
                WelcomeToTheServer view = new WelcomeToTheServer();
                view.setVisible(true);
                throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
            }

        });
    }
    else
    {
        wrong.setVisible(true);
    }

}                                     

private void signUpActionPerformed(java.awt.event.ActionEvent evt) {                                       
    // start NewUser JFrame
     signUp.addActionListener(new ActionListener()
        {
            @Override
            public void actionPerformed(ActionEvent ae) {
                NewUser new_userjframe = new NewUser();
                new_userjframe.setVisible(true);
                throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
            }

        });
}                                      

/**
 * @param args the command line arguments
 */
public static void main(String args[]) {
    /* Set the Nimbus look and feel */
    //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
    /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
     * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
     */
    try {
        for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
            if ("Nimbus".equals(info.getName())) {
                javax.swing.UIManager.setLookAndFeel(info.getClassName());
                break;
            }
        }
    } catch (ClassNotFoundException ex) {
        java.util.logging.Logger.getLogger(MainLogIn.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (InstantiationException ex) {
        java.util.logging.Logger.getLogger(MainLogIn.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (IllegalAccessException ex) {
        java.util.logging.Logger.getLogger(MainLogIn.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (javax.swing.UnsupportedLookAndFeelException ex) {
        java.util.logging.Logger.getLogger(MainLogIn.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    }
    //</editor-fold>

    /* Create and display the form */
    java.awt.EventQueue.invokeLater(new Runnable() {
        public void run() {
            new MainLogIn().setVisible(true);
        }
    });
}

// Variables declaration - do not modify                     
private javax.swing.JButton LogIn;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JPasswordField password;
private javax.swing.JButton signUp;
private javax.swing.JTextField username;
private javax.swing.JLabel wrong;
// End of variables declaration

}

when I try

LogIn.addActionListener(new ActionListener()
        {
            @Override
            public void actionPerformed(ActionEvent ae) {
                WelcomeToTheServer view = new WelcomeToTheServer();
                view.setVisible(true);
                throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
            }

        });

nothig happens. Did I write the ActionListener wrong?

Thank you

*"I created a couple of JFrames"* 1) Use a [`CardLayout`](http://download.oracle.com/javase/8/docs/api/java/awt/CardLayout.html) as shown in [this answer](http://stackoverflow.com/a/5786005/418556). 2) See [The Use of Multiple JFrames, Good/Bad Practice?](http://stackoverflow.com/q/9554636/418556) 3) See [Detection/fix for the hanging close bracket of a code block](http://meta.stackexchange.com/q/251795/155831) for a problem I could no longer be bothered fixing. — Andrew Thompson, Jun 14 '16 at 00:58

score 0 · Answer 1 · answered Jun 13 '16 at 22:08

You're initialising LogIn (and other components) twice, causing the second to overwrite what you've already set up

First in initialiseComponents() and secondly, as soon as you return

By updating your MainLogIn() constructor to:

public MainLogIn() {
    initComponents();
}

You can remove both the duplication and the issue

JButton in JFrame does not work

1 Answers1