Make button change color when mouse moves over it

I am trying to make  the color of my exit button ( jButtonExit  )change when I move a mouse over it ( aka I'm playing with events ).  I have the following event handler that makes my program not compile.  What am I doing wrong?
private void jButtonExitMouseEntered(java.awt.event.MouseEvent evt) {
    jButtonExit.setBackground(Color.BLUE);
}

Open in new window

dwcroninAsked:
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

x
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Bart CremersJava ArchitectCommented:
The code snippet you provide should compile. You'll need to provide more code to show the problem.
0
dwcroninAuthor Commented:
Bart Cr,
I am trying to learn NetBeans while I learn Java.  This code comes from following the NetBeans help files.  I'm telling you this to let you know I don't understand which files are important.  I zipped my entire directory for you but I think EE won't let me include my .java file in the archive ( I think it;s the most important one ).  Here it is below:  ( tell me if you need more )
/*
 * NumberAdditionUI.java
 *
 * Created on November 8, 2008, 8:06 AM
 */
package my.numberaddition;
 
/**
 *
 * @author  dwcronin
 */
public class NumberAdditionUI extends javax.swing.JFrame
{
 
    /** Creates new form NumberAdditionUI */
    public NumberAdditionUI()
    {
        initComponents();
    }
 
    /** 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() {
 
        jPanel1 = new javax.swing.JPanel();
        jLabelFirstNumber = new javax.swing.JLabel();
        jLabelResult = new javax.swing.JLabel();
        jLabelSecondNumber = new javax.swing.JLabel();
        jTextFieldFirstNumber = new javax.swing.JTextField();
        jTextFieldSecondNumber = new javax.swing.JTextField();
        jTextFieldResult = new javax.swing.JTextField();
        jButtonAdd = new javax.swing.JButton();
        jButtonClear = new javax.swing.JButton();
        jLabel1 = new javax.swing.JLabel();
        jButtonExit = new javax.swing.JButton();
 
        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
 
        jPanel1.setBorder(javax.swing.BorderFactory.createTitledBorder("Number Addition"));
 
        jLabelFirstNumber.setText("First Number");
 
        jLabelResult.setText("Result");
 
        jLabelSecondNumber.setText("Second Number");
 
        jTextFieldFirstNumber.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jTextFieldFirstNumberActionPerformed(evt);
            }
        });
 
        jButtonAdd.setText("Add");
        jButtonAdd.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButtonAddActionPerformed(evt);
            }
        });
 
        jButtonClear.setText("Clear");
        jButtonClear.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButtonClearActionPerformed(evt);
            }
        });
 
        jLabel1.setText("jLabel1");
 
        javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
        jPanel1.setLayout(jPanel1Layout);
        jPanel1Layout.setHorizontalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel1Layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
                        .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(jLabelFirstNumber, javax.swing.GroupLayout.Alignment.TRAILING)
                            .addComponent(jLabelSecondNumber, javax.swing.GroupLayout.Alignment.TRAILING)
                            .addComponent(jLabelResult, javax.swing.GroupLayout.Alignment.TRAILING))
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                        .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                            .addGroup(jPanel1Layout.createSequentialGroup()
                                .addComponent(jButtonAdd)
                                .addGap(41, 41, 41)
                                .addComponent(jButtonClear))
                            .addComponent(jTextFieldFirstNumber, javax.swing.GroupLayout.DEFAULT_SIZE, 290, Short.MAX_VALUE)
                            .addComponent(jTextFieldSecondNumber)
                            .addComponent(jTextFieldResult)))
                    .addComponent(jLabel1))
                .addContainerGap())
        );
 
        jPanel1Layout.linkSize(javax.swing.SwingConstants.HORIZONTAL, new java.awt.Component[] {jButtonAdd, jButtonClear});
 
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel1Layout.createSequentialGroup()
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabelFirstNumber)
                    .addComponent(jTextFieldFirstNumber, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabelSecondNumber)
                    .addComponent(jTextFieldSecondNumber, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(jPanel1Layout.createSequentialGroup()
                        .addGap(3, 3, 3)
                        .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                            .addComponent(jLabelResult)
                            .addComponent(jTextFieldResult, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addGap(46, 46, 46)
                        .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                            .addComponent(jButtonAdd)
                            .addComponent(jButtonClear)))
                    .addGroup(jPanel1Layout.createSequentialGroup()
                        .addGap(51, 51, 51)
                        .addComponent(jLabel1)))
                .addContainerGap(30, Short.MAX_VALUE))
        );
 
        jButtonExit.setText("Exit");
        jButtonExit.addMouseListener(new java.awt.event.MouseAdapter() {
            public void mouseEntered(java.awt.event.MouseEvent evt) {
                jButtonExitMouseEntered(evt);
            }
        });
        jButtonExit.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButtonExitActionPerformed(evt);
            }
        });
 
        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                    .addComponent(jButtonExit, javax.swing.GroupLayout.Alignment.TRAILING))
                .addContainerGap())
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(24, 24, 24)
                .addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addComponent(jButtonExit)
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
        );
 
        pack();
    }// </editor-fold>                        
 
private void jButtonClearActionPerformed(java.awt.event.ActionEvent evt) {                                             
    jTextFieldFirstNumber.setText("");
    jTextFieldSecondNumber.setText("");
    jTextFieldResult.setText("");
}                                            
 
private void jButtonExitActionPerformed(java.awt.event.ActionEvent evt) {                                            
    System.exit(0);
}                                           
 
private void jTextFieldFirstNumberActionPerformed(java.awt.event.ActionEvent evt) {                                                      
// TODO add your handling code here:
}                                                     
 
private void jButtonAddActionPerformed(java.awt.event.ActionEvent evt) {                                           
 
 
 
    // First we define float variables.
    float num1, num2, result;
    // We have to parse the text to a type float.
    num1 = Float.parseFloat(jTextFieldFirstNumber.getText());
    num2 = Float.parseFloat(jTextFieldSecondNumber.getText());
    // Now we can perform the addition.
    result = num1 + num2;
    // We will now pass the value of result to jTextField3.
    // At the same time, we are going to
    // change the value of result from a float to a string.
    jTextFieldResult.setText(String.valueOf(result));
}                                          
 
private void jButtonExitMouseEntered(java.awt.event.MouseEvent evt) {                                         
    jButtonExit.setBackground(Color.BLUE);                                        
}
 
    /**
    * @param args the command line arguments
    */
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new NumberAdditionUI().setVisible(true);
            }
        });
    }
 
    // Variables declaration - do not modify                     
    private javax.swing.JButton jButtonAdd;
    private javax.swing.JButton jButtonClear;
    private javax.swing.JButton jButtonExit;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabelFirstNumber;
    private javax.swing.JLabel jLabelResult;
    private javax.swing.JLabel jLabelSecondNumber;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JTextField jTextFieldFirstNumber;
    private javax.swing.JTextField jTextFieldResult;
    private javax.swing.JTextField jTextFieldSecondNumber;
    // End of variables declaration                   
 
}

Open in new window

0
Bart CremersJava ArchitectCommented:
Look like you're missing an import for java.awt.Color. You should add a line before the class declaration:


    import java.awt.Color;
   
    ...

    public class NumberAdditionUI extends ...


or you could use a fully-qualified name in the code like you've got in many other places:

    jButtonExit.setBackground(java.awt.Color.BLUE);

0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
dwcroninAuthor Commented:
I think what Bart Cr said is right.  The import MAY have already been there though and I was just getting impatient.  When I got out of netbeans and restarted it - it worked properly and I don't think I added the line (it was already in my code).  It just needed (???) restarting.  Sorry - I don't know what just happened.
0
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Editors IDEs

From novice to tech pro — start learning today.