Chamando formulario

Galera estou tentando chamar um formulário de cadastro de clientes, mais ta dando esse erro alguem me ajuda:

run:
Exception in thread “AWT-EventQueue-0” java.lang.NullPointerException
at javax.swing.ImageIcon.(ImageIcon.java:217)
at cadastros.cad_clientes.initComponents(cad_clientes.java:93)
at cadastros.cad_clientes.(cad_clientes.java:20)
at TelaPrincipal.MenuItem_ClientesActionPerformed(TelaPrincipal.java:311)
at TelaPrincipal.access$500(TelaPrincipal.java:13)
at TelaPrincipal$6.actionPerformed(TelaPrincipal.java:156)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.AbstractButton.doClick(AbstractButton.java:376)
at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:833)
at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:877)
at java.awt.Component.processMouseEvent(Component.java:6533)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
at java.awt.Component.processEvent(Component.java:6298)
at java.awt.Container.processEvent(Container.java:2236)
at java.awt.Component.dispatchEventImpl(Component.java:4889)
at java.awt.Container.dispatchEventImpl(Container.java:2294)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4525)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4466)
at java.awt.Container.dispatchEventImpl(Container.java:2280)
at java.awt.Window.dispatchEventImpl(Window.java:2746)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
at java.awt.EventQueue$4.run(EventQueue.java:731)
at java.awt.EventQueue$4.run(EventQueue.java:729)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

Posta o código aí…

import cadastros.cad_clientes;
import javax.swing.*;
public final class TelaPrincipal extends javax.swing.JFrame {
    String seta_look = "javax.swing.plaf.metal.MetalLookAndFeel";
    data mostra_data;
/**
     * Creates new form TelaPrincipal
     */
    public TelaPrincipal() {
        initComponents();
        mostra_data = new data();
        mostra_data.le_data();
        label_data.setText("Data:"+mostra_data.dia+"/"+mostra_data.mes+"/"+mostra_data.ano);
       
        timer1.start();
        
        lookandfeel();
      
       
        
    }

    /**
     * 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() {

        timer1 = new org.netbeans.examples.lib.timerbean.Timer();
        jPanel1 = new javax.swing.JPanel();
        jButton_Clientes = new javax.swing.JButton();
        jButton_produtos = new javax.swing.JButton();
        jButton_fornecedor = new javax.swing.JButton();
        jButton_sair = new javax.swing.JButton();
        label_data = new javax.swing.JLabel();
        label_hora = new javax.swing.JLabel();
        jMenuBar1 = new javax.swing.JMenuBar();
        Menu_cadastro = new javax.swing.JMenu();
        MenuItem_Clientes = new javax.swing.JMenuItem();
        MenuItem_Produtos = new javax.swing.JMenuItem();
        MenuItem_Fornecedores = new javax.swing.JMenuItem();
        Menu_consultas = new javax.swing.JMenu();
        Menu_relatorio = new javax.swing.JMenu();
        jMenu4_utilitarios = new javax.swing.JMenu();
        jMenuItem1_temawindows = new javax.swing.JMenuItem();
        jMenuItem1_temametal = new javax.swing.JMenuItem();
        jMenuItem1_temamotif = new javax.swing.JMenuItem();
        jMenuItem1_temanimbus = new javax.swing.JMenuItem();
        jMenu5 = new javax.swing.JMenu();

        timer1.addTimerListener(new org.netbeans.examples.lib.timerbean.TimerListener() {
            public void onTime(java.awt.event.ActionEvent evt) {
                timer1OnTime(evt);
            }
        });

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setTitle("Sistema de Pedidos");

        jPanel1.setBackground(new java.awt.Color(204, 204, 204));

        jButton_Clientes.setIcon(new javax.swing.ImageIcon(getClass().getResource("/imagens/icon_clientes.gif"))); // NOI18N
        jButton_Clientes.setText("Clientes");
        jButton_Clientes.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton_ClientesActionPerformed(evt);
            }
        });

        jButton_produtos.setIcon(new javax.swing.ImageIcon(getClass().getResource("/imagens/icon_produto.gif"))); // NOI18N
        jButton_produtos.setText("Produtos");
        jButton_produtos.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton_produtosActionPerformed(evt);
            }
        });

        jButton_fornecedor.setIcon(new javax.swing.ImageIcon(getClass().getResource("/imagens/icon_fornecedores.png"))); // NOI18N
        jButton_fornecedor.setText("Fornecedor");
        jButton_fornecedor.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton_fornecedorActionPerformed(evt);
            }
        });

        jButton_sair.setIcon(new javax.swing.ImageIcon(getClass().getResource("/imagens/sair.png"))); // NOI18N
        jButton_sair.setText("Sair");
        jButton_sair.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton_sairActionPerformed(evt);
            }
        });

        label_data.setFont(new java.awt.Font("Tahoma", 1, 12)); // NOI18N
        label_data.setIcon(new javax.swing.ImageIcon(getClass().getResource("/imagens/data.png"))); // NOI18N
        label_data.setText("Data: ");

        label_hora.setFont(new java.awt.Font("Tahoma", 1, 12)); // NOI18N
        label_hora.setIcon(new javax.swing.ImageIcon(getClass().getResource("/imagens/hora.png"))); // NOI18N
        label_hora.setText("Hora: ");

        javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
        jPanel1.setLayout(jPanel1Layout);
        jPanel1Layout.setHorizontalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel1Layout.createSequentialGroup()
                .addGap(40, 40, 40)
                .addComponent(jButton_Clientes, javax.swing.GroupLayout.PREFERRED_SIZE, 115, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(29, 29, 29)
                .addComponent(jButton_produtos, javax.swing.GroupLayout.PREFERRED_SIZE, 122, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(26, 26, 26)
                .addComponent(jButton_fornecedor, javax.swing.GroupLayout.PREFERRED_SIZE, 134, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(37, 37, 37)
                .addComponent(jButton_sair, javax.swing.GroupLayout.PREFERRED_SIZE, 108, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(185, 185, 185)
                .addComponent(label_data, javax.swing.GroupLayout.PREFERRED_SIZE, 238, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(27, 27, 27)
                .addComponent(label_hora)
                .addContainerGap(275, Short.MAX_VALUE))
        );
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
                .addGap(29, 29, 29)
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jButton_produtos, javax.swing.GroupLayout.PREFERRED_SIZE, 39, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jButton_Clientes, javax.swing.GroupLayout.PREFERRED_SIZE, 39, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jButton_fornecedor, javax.swing.GroupLayout.PREFERRED_SIZE, 39, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jButton_sair, javax.swing.GroupLayout.PREFERRED_SIZE, 39, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(label_data)
                    .addComponent(label_hora))
                .addContainerGap(693, Short.MAX_VALUE))
        );

        Menu_cadastro.setMnemonic('c');
        Menu_cadastro.setText("Cadastro");

        MenuItem_Clientes.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_C, java.awt.event.InputEvent.ALT_MASK));
        MenuItem_Clientes.setIcon(new javax.swing.ImageIcon(getClass().getResource("/imagens/icon_clientes.gif"))); // NOI18N
        MenuItem_Clientes.setText("Clientes");
        MenuItem_Clientes.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                MenuItem_ClientesActionPerformed(evt);
            }
        });
        Menu_cadastro.add(MenuItem_Clientes);

        MenuItem_Produtos.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_P, java.awt.event.InputEvent.ALT_MASK));
        MenuItem_Produtos.setIcon(new javax.swing.ImageIcon(getClass().getResource("/imagens/icon_produto.gif"))); // NOI18N
        MenuItem_Produtos.setText("Produtos");
        Menu_cadastro.add(MenuItem_Produtos);

        MenuItem_Fornecedores.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_F, java.awt.event.InputEvent.ALT_MASK));
        MenuItem_Fornecedores.setIcon(new javax.swing.ImageIcon(getClass().getResource("/imagens/icon_fornecedores.png"))); // NOI18N
        MenuItem_Fornecedores.setText("Fornecedores");
        Menu_cadastro.add(MenuItem_Fornecedores);

        jMenuBar1.add(Menu_cadastro);

        Menu_consultas.setMnemonic('n');
        Menu_consultas.setText("Consultas");
        jMenuBar1.add(Menu_consultas);

        Menu_relatorio.setMnemonic('r');
        Menu_relatorio.setText("Relatórios");
        jMenuBar1.add(Menu_relatorio);

        jMenu4_utilitarios.setMnemonic('u');
        jMenu4_utilitarios.setText("Utilitarios");

        jMenuItem1_temawindows.setText("Tema Windows");
        jMenuItem1_temawindows.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jMenuItem1_temawindowsActionPerformed(evt);
            }
        });
        jMenu4_utilitarios.add(jMenuItem1_temawindows);

        jMenuItem1_temametal.setText("Tema Metal");
        jMenuItem1_temametal.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jMenuItem1_temametalActionPerformed(evt);
            }
        });
        jMenu4_utilitarios.add(jMenuItem1_temametal);

        jMenuItem1_temamotif.setText("Tema Motif");
        jMenuItem1_temamotif.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jMenuItem1_temamotifActionPerformed(evt);
            }
        });
        jMenu4_utilitarios.add(jMenuItem1_temamotif);

        jMenuItem1_temanimbus.setText("Tema Nimbus");
        jMenuItem1_temanimbus.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jMenuItem1_temanimbusActionPerformed(evt);
            }
        });
        jMenu4_utilitarios.add(jMenuItem1_temanimbus);

        jMenuBar1.add(jMenu4_utilitarios);

        jMenu5.setMnemonic('s');
        jMenu5.setText("Sair");
        jMenu5.addMouseListener(new java.awt.event.MouseAdapter() {
            public void mouseClicked(java.awt.event.MouseEvent evt) {
                jMenu5MouseClicked(evt);
            }
            public void mouseExited(java.awt.event.MouseEvent evt) {
                jMenu5MouseExited(evt);
            }
        });
        jMenuBar1.add(jMenu5);

        setJMenuBar(jMenuBar1);

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(0, 71, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addContainerGap())
        );

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

    private void jButton_ClientesActionPerformed(java.awt.event.ActionEvent evt) {                                                 
        // TODO add your handling code here:
       
    }                                                

    private void jButton_produtosActionPerformed(java.awt.event.ActionEvent evt) {                                                 
        // TODO add your handling code here:
    }                                                

    private void jButton_fornecedorActionPerformed(java.awt.event.ActionEvent evt) {                                                   
        // TODO add your handling code here:
    }                                                  

    private void jButton_sairActionPerformed(java.awt.event.ActionEvent evt) {                                             
        // TODO add your handling code here:
        System.exit(0);
    }                                            

    private void jMenu5MouseExited(java.awt.event.MouseEvent evt) {                                   
        // TODO add your handling code here:
        
    }                                  

    private void jMenu5MouseClicked(java.awt.event.MouseEvent evt) {                                    
        // TODO add your handling code here:
       
        System.exit(0);
    }                                   

    private void jMenuItem1_temawindowsActionPerformed(java.awt.event.ActionEvent evt) {                                                       
        // TODO add your handling code here:
        seta_look="com.sun.java.swing.plaf.windows.WindowsLookAndFeel";
        lookandfeel();
    }                                                      

    private void jMenuItem1_temametalActionPerformed(java.awt.event.ActionEvent evt) {                                                     
        // TODO add your handling code here:
        seta_look="javax.swing.plaf.metal.MetalLookAndFeel";
        lookandfeel();
    }                                                    

    private void jMenuItem1_temamotifActionPerformed(java.awt.event.ActionEvent evt) {                                                     
        // TODO add your handling code here:
        seta_look="com.sun.java.swing.plaf.motif.MotifLookAndFeel";
        lookandfeel();
    }                                                    

    private void jMenuItem1_temanimbusActionPerformed(java.awt.event.ActionEvent evt) {                                                      
        // TODO add your handling code here:
        seta_look="com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel";
        lookandfeel();
    }                                                     

    private void timer1OnTime(java.awt.event.ActionEvent evt) {                              
        // TODO add your handling code here:
        mostra_data.le_hora();
        label_hora.setText("Hora: "+mostra_data.hora);
    }                             

    private void MenuItem_ClientesActionPerformed(java.awt.event.ActionEvent evt) {                                                  
        // TODO add your handling code here:
        cad_clientes tela = new cad_clientes();
        tela.setVisible(true);
    }                                                 

    /**
     * @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(TelaPrincipal.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(TelaPrincipal.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(TelaPrincipal.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(TelaPrincipal.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(() -> {
            new TelaPrincipal().setVisible(true);
        });
    }

    // Variables declaration - do not modify                     
    private javax.swing.JMenuItem MenuItem_Clientes;
    private javax.swing.JMenuItem MenuItem_Fornecedores;
    private javax.swing.JMenuItem MenuItem_Produtos;
    private javax.swing.JMenu Menu_cadastro;
    private javax.swing.JMenu Menu_consultas;
    private javax.swing.JMenu Menu_relatorio;
    private javax.swing.JButton jButton_Clientes;
    private javax.swing.JButton jButton_fornecedor;
    private javax.swing.JButton jButton_produtos;
    private javax.swing.JButton jButton_sair;
    private javax.swing.JMenu jMenu4_utilitarios;
    private javax.swing.JMenu jMenu5;
    private javax.swing.JMenuBar jMenuBar1;
    private javax.swing.JMenuItem jMenuItem1_temametal;
    private javax.swing.JMenuItem jMenuItem1_temamotif;
    private javax.swing.JMenuItem jMenuItem1_temanimbus;
    private javax.swing.JMenuItem jMenuItem1_temawindows;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JLabel label_data;
    private javax.swing.JLabel label_hora;
    private org.netbeans.examples.lib.timerbean.Timer timer1;
    // End of variables declaration                   

    /**
     *
     */
public  void lookandfeel(){
      try
        {
            UIManager.setLookAndFeel(seta_look);
            SwingUtilities.updateComponentTreeUI(this);
        }
        catch(ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException erro)
        {
            JOptionPane.showMessageDialog(null, erro);
        }
}
        
}

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