jLabel MouseEvent, Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException



I want to make button with hover using jLabel. When I come over button errors appears. I'm using netbeans. Most of the codes generated automatically.

public class anaEkrn extends javax.swing.JFrame {

public anaEkrn() {
    initComponents();
}
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code"> 
                        
private void initComponents() {

    jPanel1 = new javax.swing.JPanel();
    jLabel1 = new javax.swing.JLabel();

   
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

    jLabel1.setIcon(new
javax.swing.ImageIcon(getClass().getResource("/market2/images/tumu.png")));
// NOI18N
    jLabel1.setText("jLabel1");
    jLabel1.addMouseListener(new java.awt.event.MouseAdapter() {
        public void mouseEntered(java.awt.event.MouseEvent evt) {
            jLabel1MouseEntered(evt);
        }
        public void mousePressed(java.awt.event.MouseEvent evt) {
            jLabel1MousePressed(evt);
        }
    });

    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()
            .addComponent(jLabel1,
javax.swing.GroupLayout.PREFERRED_SIZE, 79,
javax.swing.GroupLayout.PREFERRED_SIZE)
            .addContainerGap(197, Short.MAX_VALUE))
    );
    jPanel1Layout.setVerticalGroup(
       
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(jPanel1Layout.createSequentialGroup()
            .addContainerGap()
            .addComponent(jLabel1,
javax.swing.GroupLayout.PREFERRED_SIZE, 97,
javax.swing.GroupLayout.PREFERRED_SIZE)
            .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE,
Short.MAX_VALUE))
    );

    javax.swing.GroupLayout layout = new
javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
       
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(javax.swing.GroupLayout.Alignment.TRAILING,
layout.createSequentialGroup()
            .addContainerGap(298, Short.MAX_VALUE)
            .addComponent(jPanel1,
javax.swing.GroupLayout.PREFERRED_SIZE,
javax.swing.GroupLayout.DEFAULT_SIZE,
javax.swing.GroupLayout.PREFERRED_SIZE)
            .addGap(23, 23, 23))
    );
    layout.setVerticalGroup(
       
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addGap(19, 19, 19)
            .addComponent(jPanel1,
javax.swing.GroupLayout.PREFERRED_SIZE,
javax.swing.GroupLayout.DEFAULT_SIZE,
javax.swing.GroupLayout.PREFERRED_SIZE)
            .addContainerGap(328, Short.MAX_VALUE))
    );

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

private void jLabel1MouseEntered(java.awt.event.MouseEvent evt) {     
                               
    ImageIcon icon= new
ImageIcon(getClass().getResource("/images/tumu.png"));
    jLabel1.setIcon(icon);
}                                    

private void jLabel1MousePressed(java.awt.event.MouseEvent evt) {     
                               
    ImageIcon II = new
ImageIcon(getClass().getResource("/images/tumu_hover.png"));
    jLabel1.setIcon(II);
}                                    

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(anaEkrn.class.getName()).log(java.util.logging.Level.SEVERE,
null, ex);
    } catch (InstantiationException ex) {
       
java.util.logging.Logger.getLogger(anaEkrn.class.getName()).log(java.util.logging.Level.SEVERE,
null, ex);
    } catch (IllegalAccessException ex) {
       
java.util.logging.Logger.getLogger(anaEkrn.class.getName()).log(java.util.logging.Level.SEVERE,
null, ex);
    } catch (javax.swing.UnsupportedLookAndFeelException ex) {
       
java.util.logging.Logger.getLogger(anaEkrn.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 anaEkrn().setVisible(true);
        }
    });
}

// Variables declaration - do not modify                     
public javax.swing.JLabel jLabel1;
private javax.swing.JPanel jPanel1;
// End of variables declaration                   

There are so many errors under this error title.

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException

What should I do?


Related to : jLabel MouseEvent, Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException

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