Erro java.lang.nullpointerexception?

Programação Java
#1

Estou com um problema. Sou novo na area de java. Criei um menu de relatório e quando vou abrir o relatório apresenta o erro java.lang.nullpointerexception. Uso o Netbeans e IReport.

public class TelaPrincipal extends javax.swing.JFrame {

    ConexaoBD conecta = new ConexaoBD();
    FormMedico tela = new FormMedico();
    FormUsuario telaUsu = new FormUsuario();
    Connection conexao = null;
                
    public TelaPrincipal(String usuario) {
        initComponents();
        jLabelUsuario.setText(usuario);
        conecta.conexao();
        int flag = 0;

    }

private void jMenuItemUsuCadActionPerformed(java.awt.event.ActionEvent evt) {                                                
        int confirma = JOptionPane.showConfirmDialog(null, "Confirma a impressão desse relatório?","Atenção", JOptionPane.YES_NO_OPTION);
        if (confirma == JOptionPane.YES_OPTION){
            try {
                JasperPrint print = JasperFillManager.fillReport("C:/Relatorios_ireport/Relatorio_usu.jasper",null,conexao);
                JasperViewer.viewReport(print,false);
            } catch (Exception e) {
                JOptionPane.showMessageDialog(null, e);
            }
        }
    }
#2

O erro deve ocorrer nesta linha, tendo em vista que você só declara o objeto conexao, sem instanciá-lo.

#3

colocar a log completa do console

#4 
package visao;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.sql.SQLException;
import javax.swing.JOptionPane;
import modeloConection.ConexaoBD;
import java.util.Date;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import javax.swing.Timer;
import java.sql.Connection;
import net.sf.jasperreports.engine.JRException;
import net.sf.jasperreports.engine.JasperFillManager;
import net.sf.jasperreports.engine.JasperPrint;
import net.sf.jasperreports.view.JasperViewer;


public class TelaPrincipal extends javax.swing.JFrame {

    ConexaoBD conecta = new ConexaoBD();
    FormMedico tela = new FormMedico();
    FormUsuario telaUsu = new FormUsuario();
    Connection conexao = null;
                
    public TelaPrincipal(String usuario) {
        initComponents();
        jLabelUsuario.setText(usuario);
        conecta.conexao();
        int flag = 0;

    }
    
    private TelaPrincipal() {
        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }


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

        jPanel1 = new javax.swing.JPanel();
        jLabelUsuario = new javax.swing.JLabel();
        jLabelHora = new javax.swing.JLabel();
        jLabelData = new javax.swing.JLabel();
        jLabelVazio = new javax.swing.JLabel();
        jXImagePanel1 = new org.jdesktop.swingx.JXImagePanel();
        jLabelLogo = new javax.swing.JLabel();
        jButtonLoginSair = new javax.swing.JButton();
        jButtonAgenda = new javax.swing.JButton();
        jButtonCadMedico = new javax.swing.JButton();
        jButtonCadPacientes = new javax.swing.JButton();
        jLabeImglCabecalho = new javax.swing.JLabel();
        jLabeImglCabecalho1 = new javax.swing.JLabel();
        jMenuBar1 = new javax.swing.JMenuBar();
        jMenuCadastro = new javax.swing.JMenu();
        jMenuItemCadMedico = new javax.swing.JMenuItem();
        jMenuItemCadPaciente = new javax.swing.JMenuItem();
        jMenuItemCadUsuario = new javax.swing.JMenuItem();
        jMenuRelatórios = new javax.swing.JMenu();
        jMenuItemUsuCad = new javax.swing.JMenuItem();
        jMenuFerramentas = new javax.swing.JMenu();
        jMenuSair = new javax.swing.JMenu();
        jMenuItem1 = new javax.swing.JMenuItem();
        jMenuItemSair = new javax.swing.JMenuItem();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setTitle("SystemLife (Versão 1.0)");
        setBackground(new java.awt.Color(255, 255, 255));
        addWindowListener(new java.awt.event.WindowAdapter() {
            public void windowOpened(java.awt.event.WindowEvent evt) {
                formWindowOpened(evt);
            }
        });

        jLabelUsuario.setFont(new java.awt.Font("Tahoma", 1, 12)); // NOI18N
        jLabelUsuario.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
        jLabelUsuario.setText("   ");
        jLabelUsuario.setAlignmentX(2.0F);
        jLabelUsuario.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 153, 153)));

        jLabelHora.setFont(new java.awt.Font("Tahoma", 0, 12)); // NOI18N
        jLabelHora.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
        jLabelHora.setAlignmentY(2.0F);
        jLabelHora.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 153, 153)));
        jLabelHora.setHorizontalTextPosition(javax.swing.SwingConstants.CENTER);

        jLabelData.setFont(new java.awt.Font("Tahoma", 0, 12)); // NOI18N
        jLabelData.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
        jLabelData.setAlignmentY(2.0F);
        jLabelData.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 153, 153)));
        jLabelData.setHorizontalTextPosition(javax.swing.SwingConstants.CENTER);
        jLabelData.addHierarchyBoundsListener(new java.awt.event.HierarchyBoundsListener() {
            public void ancestorMoved(java.awt.event.HierarchyEvent evt) {
            }
            public void ancestorResized(java.awt.event.HierarchyEvent evt) {
                jLabelDataAncestorResized(evt);
            }
        });

        jLabelVazio.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
        jLabelVazio.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 153, 153)));
        jLabelVazio.addHierarchyBoundsListener(new java.awt.event.HierarchyBoundsListener() {
            public void ancestorMoved(java.awt.event.HierarchyEvent evt) {
            }
            public void ancestorResized(java.awt.event.HierarchyEvent evt) {
                jLabelVazioAncestorResized(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(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addComponent(jLabelUsuario, javax.swing.GroupLayout.PREFERRED_SIZE, 150, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jLabelData, javax.swing.GroupLayout.PREFERRED_SIZE, 140, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jLabelHora, javax.swing.GroupLayout.PREFERRED_SIZE, 140, javax.swing.GroupLayout.PREFERRED_SIZE))
            .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addComponent(jLabelVazio, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, 794, Short.MAX_VALUE))
        );
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jLabelHora, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
            .addComponent(jLabelUsuario, javax.swing.GroupLayout.DEFAULT_SIZE, 20, Short.MAX_VALUE)
            .addComponent(jLabelData, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
            .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addComponent(jLabelVazio, javax.swing.GroupLayout.DEFAULT_SIZE, 20, Short.MAX_VALUE))
        );

        jXImagePanel1.setBackground(new java.awt.Color(255, 255, 255));

        jLabelLogo.setIcon(new javax.swing.ImageIcon(getClass().getResource("/imagens/Logo2.png"))); // NOI18N

        jButtonLoginSair.setBackground(new java.awt.Color(255, 255, 255));
        jButtonLoginSair.setFont(new java.awt.Font("Tahoma", 1, 18)); // NOI18N
        jButtonLoginSair.setText("SAIR");
        jButtonLoginSair.setBorder(new javax.swing.border.LineBorder(new java.awt.Color(0, 153, 153), 3, true));
        jButtonLoginSair.setCursor(new java.awt.Cursor(java.awt.Cursor.HAND_CURSOR));
        jButtonLoginSair.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButtonLoginSairActionPerformed(evt);
            }
        });

        jButtonAgenda.setBackground(new java.awt.Color(255, 255, 255));
        jButtonAgenda.setFont(new java.awt.Font("Tahoma", 1, 18)); // NOI18N
        jButtonAgenda.setText("AGENDAMENTO");
        jButtonAgenda.setToolTipText("Agendamento");
        jButtonAgenda.setBorder(new javax.swing.border.LineBorder(new java.awt.Color(0, 153, 153), 3, true));
        jButtonAgenda.setCursor(new java.awt.Cursor(java.awt.Cursor.HAND_CURSOR));
        jButtonAgenda.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButtonAgendaActionPerformed(evt);
            }
        });

        jButtonCadMedico.setBackground(new java.awt.Color(255, 255, 255));
        jButtonCadMedico.setFont(new java.awt.Font("Tahoma", 1, 18)); // NOI18N
        jButtonCadMedico.setText("MÉDICOS");
        jButtonCadMedico.setToolTipText("Médicos");
        jButtonCadMedico.setBorder(new javax.swing.border.LineBorder(new java.awt.Color(0, 153, 153), 3, true));
        jButtonCadMedico.setCursor(new java.awt.Cursor(java.awt.Cursor.HAND_CURSOR));
        jButtonCadMedico.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButtonCadMedicoActionPerformed(evt);
            }
        });

        jButtonCadPacientes.setBackground(new java.awt.Color(255, 255, 255));
        jButtonCadPacientes.setFont(new java.awt.Font("Tahoma", 1, 18)); // NOI18N
        jButtonCadPacientes.setText("NOVO ATENDIMENTO");
        jButtonCadPacientes.setToolTipText("Novo Atendimento");
        jButtonCadPacientes.setBorder(new javax.swing.border.LineBorder(new java.awt.Color(0, 153, 153), 3, true));
        jButtonCadPacientes.setCursor(new java.awt.Cursor(java.awt.Cursor.HAND_CURSOR));
        jButtonCadPacientes.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButtonCadPacientesActionPerformed(evt);
            }
        });

        jLabeImglCabecalho.setIcon(new javax.swing.ImageIcon(getClass().getResource("/imagens/cabecalho1.png"))); // NOI18N

        jLabeImglCabecalho1.setIcon(new javax.swing.ImageIcon(getClass().getResource("/imagens/cabecalho2.png"))); // NOI18N

        javax.swing.GroupLayout jXImagePanel1Layout = new javax.swing.GroupLayout(jXImagePanel1);
        jXImagePanel1.setLayout(jXImagePanel1Layout);
        jXImagePanel1Layout.setHorizontalGroup(
            jXImagePanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jLabeImglCabecalho, javax.swing.GroupLayout.PREFERRED_SIZE, 0, Short.MAX_VALUE)
            .addGroup(jXImagePanel1Layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jLabelLogo, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addContainerGap())
            .addComponent(jLabeImglCabecalho1, javax.swing.GroupLayout.PREFERRED_SIZE, 0, Short.MAX_VALUE)
            .addGroup(jXImagePanel1Layout.createSequentialGroup()
                .addGap(411, 411, 411)
                .addGroup(jXImagePanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                    .addComponent(jButtonLoginSair, javax.swing.GroupLayout.PREFERRED_SIZE, 260, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jButtonCadPacientes, javax.swing.GroupLayout.PREFERRED_SIZE, 260, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jButtonCadMedico, javax.swing.GroupLayout.PREFERRED_SIZE, 260, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jButtonAgenda, javax.swing.GroupLayout.PREFERRED_SIZE, 260, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addContainerGap(59, Short.MAX_VALUE))
        );
        jXImagePanel1Layout.setVerticalGroup(
            jXImagePanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jXImagePanel1Layout.createSequentialGroup()
                .addComponent(jLabeImglCabecalho, javax.swing.GroupLayout.PREFERRED_SIZE, 64, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addComponent(jLabelLogo, javax.swing.GroupLayout.PREFERRED_SIZE, 127, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(47, 47, 47)
                .addComponent(jButtonCadPacientes, javax.swing.GroupLayout.PREFERRED_SIZE, 50, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jButtonCadMedico, javax.swing.GroupLayout.PREFERRED_SIZE, 50, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jButtonAgenda, javax.swing.GroupLayout.PREFERRED_SIZE, 50, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jButtonLoginSair, javax.swing.GroupLayout.PREFERRED_SIZE, 50, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 94, Short.MAX_VALUE)
                .addComponent(jLabeImglCabecalho1, javax.swing.GroupLayout.PREFERRED_SIZE, 64, javax.swing.GroupLayout.PREFERRED_SIZE))
        );

        jMenuBar1.setCursor(new java.awt.Cursor(java.awt.Cursor.DEFAULT_CURSOR));

        jMenuCadastro.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 0, 0)));
        jMenuCadastro.setText("Cadastro");

        jMenuItemCadMedico.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_F2, 0));
        jMenuItemCadMedico.setText("Médicos");
        jMenuItemCadMedico.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jMenuItemCadMedicoActionPerformed(evt);
            }
        });
        jMenuCadastro.add(jMenuItemCadMedico);

        jMenuItemCadPaciente.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_F1, 0));
        jMenuItemCadPaciente.setText("Pacientes");
        jMenuCadastro.add(jMenuItemCadPaciente);

        jMenuItemCadUsuario.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_F3, 0));
        jMenuItemCadUsuario.setText("Usuários");
        jMenuItemCadUsuario.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jMenuItemCadUsuarioActionPerformed(evt);
            }
        });
        jMenuCadastro.add(jMenuItemCadUsuario);

        jMenuBar1.add(jMenuCadastro);

        jMenuRelatórios.setText("Relatórios");

        jMenuItemUsuCad.setText("Usuários cadastrados");
        jMenuItemUsuCad.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jMenuItemUsuCadActionPerformed(evt);
            }
        });
        jMenuRelatórios.add(jMenuItemUsuCad);

        jMenuBar1.add(jMenuRelatórios);

        jMenuFerramentas.setText("Ferramentas");
        jMenuBar1.add(jMenuFerramentas);

        jMenuSair.setText("Sair");
        jMenuSair.setToolTipText("Sair");

        jMenuItem1.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_F4, java.awt.event.InputEvent.CTRL_MASK));
        jMenuItem1.setIcon(new javax.swing.ImageIcon(getClass().getResource("/imagens/Button-Log-Off-icon.png"))); // NOI18N
        jMenuItem1.setText("Logout");
        jMenuItem1.setToolTipText("Logout");
        jMenuItem1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jMenuItem1ActionPerformed(evt);
            }
        });
        jMenuSair.add(jMenuItem1);

        jMenuItemSair.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_F4, java.awt.event.InputEvent.ALT_MASK));
        jMenuItemSair.setIcon(new javax.swing.ImageIcon(getClass().getResource("/imagens/exit2.png"))); // NOI18N
        jMenuItemSair.setText("Sair");
        jMenuItemSair.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jMenuItemSairActionPerformed(evt);
            }
        });
        jMenuSair.add(jMenuItemSair);

        jMenuBar1.add(jMenuSair);

        setJMenuBar(jMenuBar1);

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jXImagePanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
            .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addComponent(jXImagePanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addGap(0, 0, 0)
                .addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
        );

        setSize(new java.awt.Dimension(746, 705));
        setLocationRelativeTo(null);
    }// </editor-fold>                        

    private void jMenuItemCadMedicoActionPerformed(java.awt.event.ActionEvent evt) {                                                   
        try {
            conecta.executaSql("select * from usuarios where usu_usu ='"+jLabelUsuario.getText()+"'");
            conecta.rs.first();
            if(conecta.rs.getString("usu_tipo").equals("Administrador")){
                if(tela==null){
                    tela = new FormMedico();
                    tela.setVisible(true);
                    tela.setResizable(false);
                }else{
                    tela.setVisible(true);
                    tela.setResizable(false);
                }
                //FormMedico tela = new FormMedico();
                //tela.setVisible(true);
            }else{
                JOptionPane.showMessageDialog(rootPane, "Você não tem permissão para essa função!\n Contacte o administrador do sistema!");
                
            }
        } catch (SQLException ex) {
            JOptionPane.showMessageDialog(rootPane, "Você não tem permissão para essa função!\nContacte o administrador do sistema!");
        }
        
    }                                                  

    private void jMenuItemCadUsuarioActionPerformed(java.awt.event.ActionEvent evt) {                                                    
        try {
            conecta.executaSql("select * from usuarios where usu_usu ='"+jLabelUsuario.getText()+"'");
            conecta.rs.first();
            if(conecta.rs.getString("usu_tipo").equals("Administrador")){
                if(telaUsu==null){
                    telaUsu = new FormUsuario();
                    telaUsu.setVisible(true);
                    telaUsu.setResizable(false);
                }else{
                    telaUsu.setVisible(true);
                    telaUsu.setResizable(false);
                }
                //FormUsuario tela = new FormUsuario();
                //tela.setVisible(true);
            }else{
                JOptionPane.showMessageDialog(rootPane, "Você não tem permissão para essa função!\n Contacte o administrador do sistema!");
                
            }
        } catch (SQLException ex) {
            JOptionPane.showMessageDialog(rootPane, "Você não tem permissão para essa função!\nContacte o administrador do sistema!");
        }
    }                                                   
   
    private void formWindowOpened(java.awt.event.WindowEvent evt) {                                  

        Date dataSistema = new Date();
 SimpleDateFormat formato = new SimpleDateFormat("dd/MM/yyyy");
 jLabelData.setText(formato.format(dataSistema));

 Timer timer = new Timer(1000, new hora());
 timer.start();
}

    private Connection ConexaoBD() {
        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }

class hora implements ActionListener{
@Override     

public void actionPerformed(ActionEvent e){
 Calendar now = Calendar.getInstance();
    jLabelHora.setText((String.format("%1$tH:%1$tM:%1$tS", now)));
}

    }                                 

    private void jMenuItemSairActionPerformed(java.awt.event.ActionEvent evt) {                                              
        int i = JOptionPane.showConfirmDialog(null ,"Tem certeza que deseja sair?", "Confirmação de sair...",JOptionPane.YES_NO_OPTION);
        System.out.println("I" + i);
        if (i == JOptionPane.YES_OPTION ) {
            System.exit(0);
        } else {
            System.out.println("NAO FECHA JANELA");
            repaint();
        }

    }                                             

    private void jMenuItem1ActionPerformed(java.awt.event.ActionEvent evt) {                                           
        String usuario = null;
        TelaPrincipal tela = new TelaPrincipal(usuario);
        tela.setVisible(false);
        dispose();
        new TelaLogin().setVisible(true);
    }                                          

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

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

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

    private void jButtonCadMedicoActionPerformed(java.awt.event.ActionEvent evt) {                                                 
        try {
            conecta.executaSql("select * from usuarios where usu_usu ='"+jLabelUsuario.getText()+"'");
            conecta.rs.first();
            if(conecta.rs.getString("usu_tipo").equals("Administrador")){
                if(tela==null){
                    tela = new FormMedico();
                    tela.setVisible(true);
                    tela.setResizable(false);
                }else{
                    tela.setVisible(true);
                    tela.setResizable(false);
                }
                //FormMedico tela = new FormMedico();
                //tela.setVisible(true);
            }else{
                JOptionPane.showMessageDialog(rootPane, "Você não tem permissão para essa função!\n Contacte o administrador do sistema!");

            }
        } catch (SQLException ex) {
            JOptionPane.showMessageDialog(rootPane, "Você não tem permissão para essa função!\nContacte o administrador do sistema!");
        }
    }                                                

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

    private void jButtonLoginSairActionPerformed(java.awt.event.ActionEvent evt) {                                                 
        int i = JOptionPane.showConfirmDialog(null ,"Tem certeza que deseja sair?", "Confirmação de sair...",JOptionPane.YES_NO_OPTION);
        System.out.println("I" + i);
        if (i == JOptionPane.YES_OPTION ) {
            System.exit(0);
        } else {
            System.out.println("NAO FECHA JANELA");
            repaint();
        }
    }                                                

    private void jMenuItemUsuCadActionPerformed(java.awt.event.ActionEvent evt) {                                                
        int confirma = JOptionPane.showConfirmDialog(null, "Confirma a impressão desse relatório?","Atenção", JOptionPane.YES_NO_OPTION);
        if (confirma == JOptionPane.YES_OPTION){
            try {
                JasperPrint print = JasperFillManager.fillReport("C:/Relatorios_ireport/Relatorio_usu.jasper",null,conexao);
                JasperViewer.viewReport(print,false);
            } catch (Exception e) {
                JOptionPane.showMessageDialog(null, e);
            }
        }
    }                                               

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        String usuario = null;
        new TelaPrincipal(usuario).setVisible(true);
        /* 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 Runnable() {
            public void run() {
                new TelaPrincipal(usuario).setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify                     
    private javax.swing.JButton jButtonAgenda;
    private javax.swing.JButton jButtonCadMedico;
    private javax.swing.JButton jButtonCadPacientes;
    private javax.swing.JButton jButtonLoginSair;
    private javax.swing.JLabel jLabeImglCabecalho;
    private javax.swing.JLabel jLabeImglCabecalho1;
    private javax.swing.JLabel jLabelData;
    private javax.swing.JLabel jLabelHora;
    private javax.swing.JLabel jLabelLogo;
    private javax.swing.JLabel jLabelUsuario;
    private javax.swing.JLabel jLabelVazio;
    private javax.swing.JMenuBar jMenuBar1;
    private javax.swing.JMenu jMenuCadastro;
    private javax.swing.JMenu jMenuFerramentas;
    private javax.swing.JMenuItem jMenuItem1;
    private javax.swing.JMenuItem jMenuItemCadMedico;
    private javax.swing.JMenuItem jMenuItemCadPaciente;
    private javax.swing.JMenuItem jMenuItemCadUsuario;
    private javax.swing.JMenuItem jMenuItemSair;
    private javax.swing.JMenuItem jMenuItemUsuCad;
    private javax.swing.JMenu jMenuRelatórios;
    private javax.swing.JMenu jMenuSair;
    private javax.swing.JPanel jPanel1;
    private org.jdesktop.swingx.JXImagePanel jXImagePanel1;
    // End of variables declaration                   
}

Sendo que o erro está nessa linha.

 private void jMenuItemUsuCadActionPerformed(java.awt.event.ActionEvent evt) {                                                
        int confirma = JOptionPane.showConfirmDialog(null, "Confirma a impressão desse relatório?","Atenção", JOptionPane.YES_NO_OPTION);
        if (confirma == JOptionPane.YES_OPTION){
            try {
                JasperPrint print = JasperFillManager.fillReport("C:/Relatorios_ireport/Relatorio_usu.jasper",null,conexao);
                JasperViewer.viewReport(print,false);
            } catch (Exception e) {
                JOptionPane.showMessageDialog(null, e);
            }
        }
    }
#5

Alguém poderia me ajudar por favor?

#6

Aí cumpade, o erro está apontando para qual linha do seu código ??

Vc mexeu em algo referente ao que o nosso amigo “Luis_Augusto_Santos” descreveu? Eu começaria por aí.

#7

Quando clico em Relatório, ele apresenta a mensagem se deseja imprimir, eu clico em Sim e aparece a mensagem “java.lang.nullpointerexception”

Não mexi em nada mais. Estava sem tempo.

#8

Beleza, entendi onde ocorre. Mas e o código teu, ele aponta o erro em qual linha?

#9

Ele da construído com sucesso, não aparece em qual linha foi o erro.

package visao;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.sql.SQLException;
import javax.swing.JOptionPane;
import modeloConection.ConexaoBD;
import java.util.Date;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import javax.swing.Timer;
import java.sql.Connection;
import net.sf.jasperreports.engine.JRException;
import net.sf.jasperreports.engine.JasperFillManager;
import net.sf.jasperreports.engine.JasperPrint;
import net.sf.jasperreports.view.JasperViewer;


public class TelaPrincipal extends javax.swing.JFrame {

    ConexaoBD conecta = new ConexaoBD();
    FormMedico tela = new FormMedico();
    FormUsuario telaUsu = new FormUsuario();
    Connection conexao = null;
                
    public TelaPrincipal(String usuario) {
        initComponents();
        jLabelUsuario.setText(usuario);
        conecta.conexao();
        int flag = 0;

    }
    
    private TelaPrincipal() {
        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }


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

        jPanel1 = new javax.swing.JPanel();
        jLabelUsuario = new javax.swing.JLabel();
        jLabelHora = new javax.swing.JLabel();
        jLabelData = new javax.swing.JLabel();
        jLabelVazio = new javax.swing.JLabel();
        jXImagePanel1 = new org.jdesktop.swingx.JXImagePanel();
        jLabelLogo = new javax.swing.JLabel();
        jButtonLoginSair = new javax.swing.JButton();
        jButtonAgenda = new javax.swing.JButton();
        jButtonCadMedico = new javax.swing.JButton();
        jButtonCadPacientes = new javax.swing.JButton();
        jLabeImglCabecalho = new javax.swing.JLabel();
        jLabeImglCabecalho1 = new javax.swing.JLabel();
        jMenuBar1 = new javax.swing.JMenuBar();
        jMenuCadastro = new javax.swing.JMenu();
        jMenuItemCadMedico = new javax.swing.JMenuItem();
        jMenuItemCadPaciente = new javax.swing.JMenuItem();
        jMenuItemCadUsuario = new javax.swing.JMenuItem();
        jMenuRelatórios = new javax.swing.JMenu();
        jMenuItemUsuCad = new javax.swing.JMenuItem();
        jMenuFerramentas = new javax.swing.JMenu();
        jMenuSair = new javax.swing.JMenu();
        jMenuItem1 = new javax.swing.JMenuItem();
        jMenuItemSair = new javax.swing.JMenuItem();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setTitle("SystemLife (Versão 1.0)");
        setBackground(new java.awt.Color(255, 255, 255));
        addWindowListener(new java.awt.event.WindowAdapter() {
            public void windowOpened(java.awt.event.WindowEvent evt) {
                formWindowOpened(evt);
            }
        });

        jLabelUsuario.setFont(new java.awt.Font("Tahoma", 1, 12)); // NOI18N
        jLabelUsuario.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
        jLabelUsuario.setText("   ");
        jLabelUsuario.setAlignmentX(2.0F);
        jLabelUsuario.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 153, 153)));

        jLabelHora.setFont(new java.awt.Font("Tahoma", 0, 12)); // NOI18N
        jLabelHora.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
        jLabelHora.setAlignmentY(2.0F);
        jLabelHora.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 153, 153)));
        jLabelHora.setHorizontalTextPosition(javax.swing.SwingConstants.CENTER);

        jLabelData.setFont(new java.awt.Font("Tahoma", 0, 12)); // NOI18N
        jLabelData.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
        jLabelData.setAlignmentY(2.0F);
        jLabelData.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 153, 153)));
        jLabelData.setHorizontalTextPosition(javax.swing.SwingConstants.CENTER);
        jLabelData.addHierarchyBoundsListener(new java.awt.event.HierarchyBoundsListener() {
            public void ancestorMoved(java.awt.event.HierarchyEvent evt) {
            }
            public void ancestorResized(java.awt.event.HierarchyEvent evt) {
                jLabelDataAncestorResized(evt);
            }
        });

        jLabelVazio.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
        jLabelVazio.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 153, 153)));
        jLabelVazio.addHierarchyBoundsListener(new java.awt.event.HierarchyBoundsListener() {
            public void ancestorMoved(java.awt.event.HierarchyEvent evt) {
            }
            public void ancestorResized(java.awt.event.HierarchyEvent evt) {
                jLabelVazioAncestorResized(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(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addComponent(jLabelUsuario, javax.swing.GroupLayout.PREFERRED_SIZE, 150, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jLabelData, javax.swing.GroupLayout.PREFERRED_SIZE, 140, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jLabelHora, javax.swing.GroupLayout.PREFERRED_SIZE, 140, javax.swing.GroupLayout.PREFERRED_SIZE))
            .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addComponent(jLabelVazio, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, 794, Short.MAX_VALUE))
        );
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jLabelHora, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
            .addComponent(jLabelUsuario, javax.swing.GroupLayout.DEFAULT_SIZE, 20, Short.MAX_VALUE)
            .addComponent(jLabelData, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
            .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addComponent(jLabelVazio, javax.swing.GroupLayout.DEFAULT_SIZE, 20, Short.MAX_VALUE))
        );

        jXImagePanel1.setBackground(new java.awt.Color(255, 255, 255));

        jLabelLogo.setIcon(new javax.swing.ImageIcon(getClass().getResource("/imagens/Logo2.png"))); // NOI18N

        jButtonLoginSair.setBackground(new java.awt.Color(255, 255, 255));
        jButtonLoginSair.setFont(new java.awt.Font("Tahoma", 1, 18)); // NOI18N
        jButtonLoginSair.setText("SAIR");
        jButtonLoginSair.setBorder(new javax.swing.border.LineBorder(new java.awt.Color(0, 153, 153), 3, true));
        jButtonLoginSair.setCursor(new java.awt.Cursor(java.awt.Cursor.HAND_CURSOR));
        jButtonLoginSair.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButtonLoginSairActionPerformed(evt);
            }
        });

        jButtonAgenda.setBackground(new java.awt.Color(255, 255, 255));
        jButtonAgenda.setFont(new java.awt.Font("Tahoma", 1, 18)); // NOI18N
        jButtonAgenda.setText("AGENDAMENTO");
        jButtonAgenda.setToolTipText("Agendamento");
        jButtonAgenda.setBorder(new javax.swing.border.LineBorder(new java.awt.Color(0, 153, 153), 3, true));
        jButtonAgenda.setCursor(new java.awt.Cursor(java.awt.Cursor.HAND_CURSOR));
        jButtonAgenda.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButtonAgendaActionPerformed(evt);
            }
        });

        jButtonCadMedico.setBackground(new java.awt.Color(255, 255, 255));
        jButtonCadMedico.setFont(new java.awt.Font("Tahoma", 1, 18)); // NOI18N
        jButtonCadMedico.setText("MÉDICOS");
        jButtonCadMedico.setToolTipText("Médicos");
        jButtonCadMedico.setBorder(new javax.swing.border.LineBorder(new java.awt.Color(0, 153, 153), 3, true));
        jButtonCadMedico.setCursor(new java.awt.Cursor(java.awt.Cursor.HAND_CURSOR));
        jButtonCadMedico.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButtonCadMedicoActionPerformed(evt);
            }
        });

        jButtonCadPacientes.setBackground(new java.awt.Color(255, 255, 255));
        jButtonCadPacientes.setFont(new java.awt.Font("Tahoma", 1, 18)); // NOI18N
        jButtonCadPacientes.setText("NOVO ATENDIMENTO");
        jButtonCadPacientes.setToolTipText("Novo Atendimento");
        jButtonCadPacientes.setBorder(new javax.swing.border.LineBorder(new java.awt.Color(0, 153, 153), 3, true));
        jButtonCadPacientes.setCursor(new java.awt.Cursor(java.awt.Cursor.HAND_CURSOR));
        jButtonCadPacientes.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButtonCadPacientesActionPerformed(evt);
            }
        });

        jLabeImglCabecalho.setIcon(new javax.swing.ImageIcon(getClass().getResource("/imagens/cabecalho1.png"))); // NOI18N

        jLabeImglCabecalho1.setIcon(new javax.swing.ImageIcon(getClass().getResource("/imagens/cabecalho2.png"))); // NOI18N

        javax.swing.GroupLayout jXImagePanel1Layout = new javax.swing.GroupLayout(jXImagePanel1);
        jXImagePanel1.setLayout(jXImagePanel1Layout);
        jXImagePanel1Layout.setHorizontalGroup(
            jXImagePanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jLabeImglCabecalho, javax.swing.GroupLayout.PREFERRED_SIZE, 0, Short.MAX_VALUE)
            .addGroup(jXImagePanel1Layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jLabelLogo, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addContainerGap())
            .addComponent(jLabeImglCabecalho1, javax.swing.GroupLayout.PREFERRED_SIZE, 0, Short.MAX_VALUE)
            .addGroup(jXImagePanel1Layout.createSequentialGroup()
                .addGap(411, 411, 411)
                .addGroup(jXImagePanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                    .addComponent(jButtonLoginSair, javax.swing.GroupLayout.PREFERRED_SIZE, 260, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jButtonCadPacientes, javax.swing.GroupLayout.PREFERRED_SIZE, 260, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jButtonCadMedico, javax.swing.GroupLayout.PREFERRED_SIZE, 260, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jButtonAgenda, javax.swing.GroupLayout.PREFERRED_SIZE, 260, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addContainerGap(59, Short.MAX_VALUE))
        );
        jXImagePanel1Layout.setVerticalGroup(
            jXImagePanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jXImagePanel1Layout.createSequentialGroup()
                .addComponent(jLabeImglCabecalho, javax.swing.GroupLayout.PREFERRED_SIZE, 64, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addComponent(jLabelLogo, javax.swing.GroupLayout.PREFERRED_SIZE, 127, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(47, 47, 47)
                .addComponent(jButtonCadPacientes, javax.swing.GroupLayout.PREFERRED_SIZE, 50, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jButtonCadMedico, javax.swing.GroupLayout.PREFERRED_SIZE, 50, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jButtonAgenda, javax.swing.GroupLayout.PREFERRED_SIZE, 50, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jButtonLoginSair, javax.swing.GroupLayout.PREFERRED_SIZE, 50, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 94, Short.MAX_VALUE)
                .addComponent(jLabeImglCabecalho1, javax.swing.GroupLayout.PREFERRED_SIZE, 64, javax.swing.GroupLayout.PREFERRED_SIZE))
        );

        jMenuBar1.setCursor(new java.awt.Cursor(java.awt.Cursor.DEFAULT_CURSOR));

        jMenuCadastro.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 0, 0)));
        jMenuCadastro.setText("Cadastro");

        jMenuItemCadMedico.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_F2, 0));
        jMenuItemCadMedico.setText("Médicos");
        jMenuItemCadMedico.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jMenuItemCadMedicoActionPerformed(evt);
            }
        });
        jMenuCadastro.add(jMenuItemCadMedico);

        jMenuItemCadPaciente.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_F1, 0));
        jMenuItemCadPaciente.setText("Pacientes");
        jMenuCadastro.add(jMenuItemCadPaciente);

        jMenuItemCadUsuario.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_F3, 0));
        jMenuItemCadUsuario.setText("Usuários");
        jMenuItemCadUsuario.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jMenuItemCadUsuarioActionPerformed(evt);
            }
        });
        jMenuCadastro.add(jMenuItemCadUsuario);

        jMenuBar1.add(jMenuCadastro);

        jMenuRelatórios.setText("Relatórios");

        jMenuItemUsuCad.setText("Usuários cadastrados");
        jMenuItemUsuCad.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jMenuItemUsuCadActionPerformed(evt);
            }
        });
        jMenuRelatórios.add(jMenuItemUsuCad);

        jMenuBar1.add(jMenuRelatórios);

        jMenuFerramentas.setText("Ferramentas");
        jMenuBar1.add(jMenuFerramentas);

        jMenuSair.setText("Sair");
        jMenuSair.setToolTipText("Sair");

        jMenuItem1.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_F4, java.awt.event.InputEvent.CTRL_MASK));
        jMenuItem1.setIcon(new javax.swing.ImageIcon(getClass().getResource("/imagens/Button-Log-Off-icon.png"))); // NOI18N
        jMenuItem1.setText("Logout");
        jMenuItem1.setToolTipText("Logout");
        jMenuItem1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jMenuItem1ActionPerformed(evt);
            }
        });
        jMenuSair.add(jMenuItem1);

        jMenuItemSair.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_F4, java.awt.event.InputEvent.ALT_MASK));
        jMenuItemSair.setIcon(new javax.swing.ImageIcon(getClass().getResource("/imagens/exit2.png"))); // NOI18N
        jMenuItemSair.setText("Sair");
        jMenuItemSair.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jMenuItemSairActionPerformed(evt);
            }
        });
        jMenuSair.add(jMenuItemSair);

        jMenuBar1.add(jMenuSair);

        setJMenuBar(jMenuBar1);

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jXImagePanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
            .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addComponent(jXImagePanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addGap(0, 0, 0)
                .addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
        );

        setSize(new java.awt.Dimension(746, 705));
        setLocationRelativeTo(null);
    }// </editor-fold>                        

    private void jMenuItemCadMedicoActionPerformed(java.awt.event.ActionEvent evt) {                                                   
        try {
            conecta.executaSql("select * from usuarios where usu_usu ='"+jLabelUsuario.getText()+"'");
            conecta.rs.first();
            if(conecta.rs.getString("usu_tipo").equals("Administrador")){
                if(tela==null){
                    tela = new FormMedico();
                    tela.setVisible(true);
                    tela.setResizable(false);
                }else{
                    tela.setVisible(true);
                    tela.setResizable(false);
                }
                //FormMedico tela = new FormMedico();
                //tela.setVisible(true);
            }else{
                JOptionPane.showMessageDialog(rootPane, "Você não tem permissão para essa função!\n Contacte o administrador do sistema!");
                
            }
        } catch (SQLException ex) {
            JOptionPane.showMessageDialog(rootPane, "Você não tem permissão para essa função!\nContacte o administrador do sistema!");
        }
        
    }                                                  

    private void jMenuItemCadUsuarioActionPerformed(java.awt.event.ActionEvent evt) {                                                    
        try {
            conecta.executaSql("select * from usuarios where usu_usu ='"+jLabelUsuario.getText()+"'");
            conecta.rs.first();
            if(conecta.rs.getString("usu_tipo").equals("Administrador")){
                if(telaUsu==null){
                    telaUsu = new FormUsuario();
                    telaUsu.setVisible(true);
                    telaUsu.setResizable(false);
                }else{
                    telaUsu.setVisible(true);
                    telaUsu.setResizable(false);
                }
                //FormUsuario tela = new FormUsuario();
                //tela.setVisible(true);
            }else{
                JOptionPane.showMessageDialog(rootPane, "Você não tem permissão para essa função!\n Contacte o administrador do sistema!");
                
            }
        } catch (SQLException ex) {
            JOptionPane.showMessageDialog(rootPane, "Você não tem permissão para essa função!\nContacte o administrador do sistema!");
        }
    }                                                   
   
    private void formWindowOpened(java.awt.event.WindowEvent evt) {                                  

        Date dataSistema = new Date();
 SimpleDateFormat formato = new SimpleDateFormat("dd/MM/yyyy");
 jLabelData.setText(formato.format(dataSistema));

 Timer timer = new Timer(1000, new hora());
 timer.start();
}

    private Connection ConexaoBD() {
        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }

class hora implements ActionListener{
@Override     

public void actionPerformed(ActionEvent e){
 Calendar now = Calendar.getInstance();
    jLabelHora.setText((String.format("%1$tH:%1$tM:%1$tS", now)));
}

    }                                 

    private void jMenuItemSairActionPerformed(java.awt.event.ActionEvent evt) {                                              
        int i = JOptionPane.showConfirmDialog(null ,"Tem certeza que deseja sair?", "Confirmação de sair...",JOptionPane.YES_NO_OPTION);
        System.out.println("I" + i);
        if (i == JOptionPane.YES_OPTION ) {
            System.exit(0);
        } else {
            System.out.println("NAO FECHA JANELA");
            repaint();
        }

    }                                             

    private void jMenuItem1ActionPerformed(java.awt.event.ActionEvent evt) {                                           
        String usuario = null;
        TelaPrincipal tela = new TelaPrincipal(usuario);
        tela.setVisible(false);
        dispose();
        new TelaLogin().setVisible(true);
    }                                          

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

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

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

    private void jButtonCadMedicoActionPerformed(java.awt.event.ActionEvent evt) {                                                 
        try {
            conecta.executaSql("select * from usuarios where usu_usu ='"+jLabelUsuario.getText()+"'");
            conecta.rs.first();
            if(conecta.rs.getString("usu_tipo").equals("Administrador")){
                if(tela==null){
                    tela = new FormMedico();
                    tela.setVisible(true);
                    tela.setResizable(false);
                }else{
                    tela.setVisible(true);
                    tela.setResizable(false);
                }
                //FormMedico tela = new FormMedico();
                //tela.setVisible(true);
            }else{
                JOptionPane.showMessageDialog(rootPane, "Você não tem permissão para essa função!\n Contacte o administrador do sistema!");

            }
        } catch (SQLException ex) {
            JOptionPane.showMessageDialog(rootPane, "Você não tem permissão para essa função!\nContacte o administrador do sistema!");
        }
    }                                                

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

    private void jButtonLoginSairActionPerformed(java.awt.event.ActionEvent evt) {                                                 
        int i = JOptionPane.showConfirmDialog(null ,"Tem certeza que deseja sair?", "Confirmação de sair...",JOptionPane.YES_NO_OPTION);
        System.out.println("I" + i);
        if (i == JOptionPane.YES_OPTION ) {
            System.exit(0);
        } else {
            System.out.println("NAO FECHA JANELA");
            repaint();
        }
    }                                                

    private void jMenuItemUsuCadActionPerformed(java.awt.event.ActionEvent evt) {                                                
        int confirma = JOptionPane.showConfirmDialog(null, "Confirma a impressão desse relatório?","Atenção", JOptionPane.YES_NO_OPTION);
        if (confirma == JOptionPane.YES_OPTION){
            try {
                JasperPrint print = JasperFillManager.fillReport("C:/Relatorios_ireport/Relatorio_usu.jasper",null,conexao);
                JasperViewer.viewReport(print,false);
            } catch (Exception e) {
                JOptionPane.showMessageDialog(null, e);
            }
        }
    }                                               

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        String usuario = null;
        new TelaPrincipal(usuario).setVisible(true);
        /* 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 Runnable() {
            public void run() {
                new TelaPrincipal(usuario).setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify                     
    private javax.swing.JButton jButtonAgenda;
    private javax.swing.JButton jButtonCadMedico;
    private javax.swing.JButton jButtonCadPacientes;
    private javax.swing.JButton jButtonLoginSair;
    private javax.swing.JLabel jLabeImglCabecalho;
    private javax.swing.JLabel jLabeImglCabecalho1;
    private javax.swing.JLabel jLabelData;
    private javax.swing.JLabel jLabelHora;
    private javax.swing.JLabel jLabelLogo;
    private javax.swing.JLabel jLabelUsuario;
    private javax.swing.JLabel jLabelVazio;
    private javax.swing.JMenuBar jMenuBar1;
    private javax.swing.JMenu jMenuCadastro;
    private javax.swing.JMenu jMenuFerramentas;
    private javax.swing.JMenuItem jMenuItem1;
    private javax.swing.JMenuItem jMenuItemCadMedico;
    private javax.swing.JMenuItem jMenuItemCadPaciente;
    private javax.swing.JMenuItem jMenuItemCadUsuario;
    private javax.swing.JMenuItem jMenuItemSair;
    private javax.swing.JMenuItem jMenuItemUsuCad;
    private javax.swing.JMenu jMenuRelatórios;
    private javax.swing.JMenu jMenuSair;
    private javax.swing.JPanel jPanel1;
    private org.jdesktop.swingx.JXImagePanel jXImagePanel1;
    // End of variables declaration                   
}

Sendo que o erro está nessa linha abaixo.

 private void jMenuItemUsuCadActionPerformed(java.awt.event.ActionEvent evt) {                                                
        int confirma = JOptionPane.showConfirmDialog(null, "Confirma a impressão desse relatório?","Atenção", JOptionPane.YES_NO_OPTION);
        if (confirma == JOptionPane.YES_OPTION){
            try {
                JasperPrint print = JasperFillManager.fillReport("C:/Relatorios_ireport/Relatorio_usu.jasper",null,conexao);
                JasperViewer.viewReport(print,false);
            } catch (Exception e) {
                JOptionPane.showMessageDialog(null, e);
            }
        }
    }
#10

Substitui essa linha por isso :
e.printStackTrace();

Depois coloque a log do console.

Seu problema vai ser corrigido rapidamente

1 curtida
#11 
try {
JasperPrint print = JasperFillManager.fillReport("C:/Relatorios_ireport/Relatorio_usu.jasper",null,conexao);
JasperViewer jpView = new JasperViewer(print, false);
jpView.setVisible(true);
         
 } catch (Exception e) {
                JOptionPane.showMessageDialog(null, e);
}
#12

O que o Eduardo colocou está aparecendo a seguinte mensagem:

java.lang.NullPointerException
at net.sf.jasperreports.engine.fill.JRFiller.fillReport(JRFiller.java:63)
at net.sf.jasperreports.engine.JasperFillManager.fillReport(JasperFillManager.java:402)
at net.sf.jasperreports.engine.JasperFillManager.fillReport(JasperFillManager.java:234)
at visao.TelaPrincipal.jMenuItemUsuCadActionPerformed(TelaPrincipal.java:475)
at visao.TelaPrincipal.access$900(TelaPrincipal.java:25)
at visao.TelaPrincipal$10.actionPerformed(TelaPrincipal.java:268)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
at javax.swing.AbstractButton$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:80)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:90)
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:80)
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)
I0

O que o JavaGambiara colocou dá somentejava.lang.nullpointerexception

#13 
try {
JRResultSetDataSource relatoriResultado = new JRResultSetDataSource(conexao);
JasperPrint print = JasperFillManager.fillReport("C:/Relatorios_ireport/Relatorio_usu.jasper", new HashMap(), relatoriResultado);

JasperViewer jpView = new JasperViewer(print, false);
jpView.setVisible(true);

} catch (Exception e) {
JOptionPane.showMessageDialog(null, e);
}

Atenção nesta linha:

JRResultSetDataSource relatoriResultado = new JRResultSetDataSource(conexao);

O parâmetro conexao e para retornar uma pesquisa com os dados para preencher o relatório!

Tente desta forma!