public void establecerClienteInicio() {
   int valor =
       Integer.parseInt(JOptionPane.showInputDialog("Ingrese posicion de nodo a ingresar"));
   Prestamos pre =
       new Prestamos(
           CodigoPrestamo.getText(),
           CodigoLibro.getText(),
           Cedula.getText(),
           FechaSalida.getText(),
           FechaMaximaDevolucion.getText());
   listaPrestamos.insertarInicio(pre, valor);
   JOptionPane.showMessageDialog(null, "Se agregó un elemento a la lista");
   CodigoPrestamo.setText(null);
   CodigoLibro.setText(null);
   Cedula.setText(null);
   FechaSalida.setText(null);
   FechaMaximaDevolucion.setText(null);
   panel.setViewportView(new PanelDibujoPrestamos(listaPrestamos.size(), "", listaPrestamos));
 }
  private void calcularActionPerformed(
      java.awt.event.ActionEvent evt) { // GEN-FIRST:event_calcularActionPerformed
    // TODO add your handling code here:

    if (CodigoPrestamo.getText().trim().length() == 0) {
      JOptionPane.showMessageDialog(this, "Ingresa el Código del Préstamo");
    } else if (FechaSalida.getText().trim().length() == 0) {
      JOptionPane.showMessageDialog(this, "Ingresa la Fecha de Salida");
    } else if (Cedula.getText().trim().length() == 0) {
      JOptionPane.showMessageDialog(this, "Ingresa tu Cédula");
    } else if (CodigoLibro.getText().trim().length() == 0) {
      JOptionPane.showMessageDialog(this, "Ingresa el Código del Libro");
    } else if (FechaMaximaDevolucion.getText().trim().length() == 0) {
      JOptionPane.showMessageDialog(this, "Ingresa la Fecha Máxima de Devolución");
    } else {
      operacioneComboBox();
    }
  } // GEN-LAST:event_calcularActionPerformed
  public void operacioneComboBox() {
    if (menuoperaciones.getSelectedItem().equals("Eliminar Elemento")) {
      eliminar();
    }
    if (menuoperaciones.getSelectedItem().equals("Eliminar Lista")) {
      eliminar2();
    }

    if (menuoperaciones.getSelectedItem().equals("Eliminar Inicio")) {
      listaPrestamos.eliminarInicio();
      panel.setViewportView(new PanelDibujoPrestamos(listaPrestamos.size(), "", listaPrestamos));
    }
    if (menuoperaciones.getSelectedItem().equals("Eliminar Final")) {
      listaPrestamos.eliminarFinal();
      panel.setViewportView(new PanelDibujoPrestamos(listaPrestamos.size(), "", listaPrestamos));
    }

    if (menuoperaciones.getSelectedItem().equals("Insertar Elemento")) {
      establecerClienteInicio();
    }

    if (menuoperaciones.getSelectedItem().equals("Contar Elementos")) {
      JOptionPane.showMessageDialog(null, "El tamaño de la lista es:" + (listaPrestamos.size()));
    }

    if (menuoperaciones.getSelectedItem().equals("Modificar Elemento")) {
      int valor =
          Integer.parseInt(JOptionPane.showInputDialog("Ingrese clave del elemento a modificar"));
      Prestamos pre =
          new Prestamos(
              CodigoPrestamo.getText(),
              CodigoLibro.getText(),
              Cedula.getText(),
              FechaSalida.getText(),
              FechaMaximaDevolucion.getText());
      listaPrestamos.modificar(valor, pre);
      panel.setViewportView(new PanelDibujoPrestamos(listaPrestamos.size(), "", listaPrestamos));
    }

    if (menuoperaciones.getSelectedItem().equals("Buscar por Código del Préstamo")) {

      buscarPrestamo();
    }
  }
  /**
   * 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">//GEN-BEGIN:initComponents
  private void initComponents() {

    CodigoPrestamo = new javax.swing.JTextField();
    Cedula = new javax.swing.JTextField();
    CodigoLibro = new javax.swing.JTextField();
    buscar = new javax.swing.JButton();
    jScrollPane1 = new javax.swing.JScrollPane();
    jTextArea1 = new javax.swing.JTextArea();
    mostrar = new javax.swing.JButton();
    jButton6 = new javax.swing.JButton();
    salir = new javax.swing.JButton();
    menuoperaciones = new javax.swing.JComboBox();
    calcular = new javax.swing.JToggleButton();
    jLabel1 = new javax.swing.JLabel();
    jLabel2 = new javax.swing.JLabel();
    jLabel3 = new javax.swing.JLabel();
    panel = new javax.swing.JScrollPane();
    jLabel6 = new javax.swing.JLabel();
    jLabel7 = new javax.swing.JLabel();
    FechaSalida = new javax.swing.JTextField();
    jLabel8 = new javax.swing.JLabel();
    jLabel5 = new javax.swing.JLabel();
    FechaMaximaDevolucion = new javax.swing.JTextField();
    jLabel9 = new javax.swing.JLabel();

    setDefaultCloseOperation(javax.swing.WindowConstants.DISPOSE_ON_CLOSE);

    CodigoPrestamo.setToolTipText("Dijita el Código del Préstamo");
    CodigoPrestamo.addActionListener(
        new java.awt.event.ActionListener() {
          public void actionPerformed(java.awt.event.ActionEvent evt) {
            CodigoPrestamoActionPerformed(evt);
          }
        });

    Cedula.setToolTipText("Dijita la Cédula del Lector");
    Cedula.addActionListener(
        new java.awt.event.ActionListener() {
          public void actionPerformed(java.awt.event.ActionEvent evt) {
            CedulaActionPerformed(evt);
          }
        });

    CodigoLibro.setToolTipText("Dijita el Código del Libro");
    CodigoLibro.addActionListener(
        new java.awt.event.ActionListener() {
          public void actionPerformed(java.awt.event.ActionEvent evt) {
            CodigoLibroActionPerformed(evt);
          }
        });

    buscar.setText("Buscar");
    buscar.setToolTipText("Busca por clave de el nodo");
    buscar.addActionListener(
        new java.awt.event.ActionListener() {
          public void actionPerformed(java.awt.event.ActionEvent evt) {
            buscarActionPerformed(evt);
          }
        });

    jTextArea1.setColumns(20);
    jTextArea1.setRows(5);
    jScrollPane1.setViewportView(jTextArea1);

    mostrar.setText("Mostrar");
    mostrar.setToolTipText("Muestra los nodos Ingresados");
    mostrar.addActionListener(
        new java.awt.event.ActionListener() {
          public void actionPerformed(java.awt.event.ActionEvent evt) {
            mostrarActionPerformed(evt);
          }
        });

    jButton6.setText("Limpiar");
    jButton6.setToolTipText("Limpia la tabla de Nodos");
    jButton6.addActionListener(
        new java.awt.event.ActionListener() {
          public void actionPerformed(java.awt.event.ActionEvent evt) {
            jButton6ActionPerformed(evt);
          }
        });

    salir.setText("Salir");
    salir.setToolTipText("Sale del Sistema");
    salir.addActionListener(
        new java.awt.event.ActionListener() {
          public void actionPerformed(java.awt.event.ActionEvent evt) {
            salirActionPerformed(evt);
          }
        });

    menuoperaciones.setModel(
        new javax.swing.DefaultComboBoxModel(
            new String[] {
              "Insertar Elemento",
              "Modificar Elemento",
              "Buscar por Código del Préstamo",
              "Contar Elementos",
              "Eliminar Elemento",
              "Eliminar Inicio",
              "Eliminar Final",
              "Eliminar Lista",
              " "
            }));
    menuoperaciones.addActionListener(
        new java.awt.event.ActionListener() {
          public void actionPerformed(java.awt.event.ActionEvent evt) {
            menuoperacionesActionPerformed(evt);
          }
        });

    calcular.setText("Aceptar");
    calcular.addActionListener(
        new java.awt.event.ActionListener() {
          public void actionPerformed(java.awt.event.ActionEvent evt) {
            calcularActionPerformed(evt);
          }
        });

    jLabel1.setText("* Código del Préstamo:");

    jLabel2.setText("* Cédula:");

    jLabel3.setText("* Código del Libro:");

    jLabel6.setFont(new java.awt.Font("Georgia", 1, 24)); // NOI18N
    jLabel6.setText("Préstamos");

    jLabel7.setFont(new java.awt.Font("Ubuntu", 1, 13)); // NOI18N
    jLabel7.setForeground(new java.awt.Color(202, 37, 37));
    jLabel7.setText("Grafico:");

    FechaSalida.setToolTipText("Día/Mes/Año");
    FechaSalida.addActionListener(
        new java.awt.event.ActionListener() {
          public void actionPerformed(java.awt.event.ActionEvent evt) {
            FechaSalidaActionPerformed(evt);
          }
        });

    jLabel8.setText("* Fecha de Salida:");

    jLabel5.setForeground(new java.awt.Color(255, 0, 0));
    jLabel5.setText("Campos marcados con asterisco (*) son obligatorios");

    FechaMaximaDevolucion.setToolTipText("Día/Mes/Año");
    FechaMaximaDevolucion.addActionListener(
        new java.awt.event.ActionListener() {
          public void actionPerformed(java.awt.event.ActionEvent evt) {
            FechaMaximaDevolucionActionPerformed(evt);
          }
        });

    jLabel9.setText("* Fecha Máxima de Devolución:");

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout
            .createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(
                layout
                    .createSequentialGroup()
                    .addGap(247, 247, 247)
                    .addComponent(jLabel8)
                    .addGap(0, 0, Short.MAX_VALUE))
            .addGroup(
                layout
                    .createSequentialGroup()
                    .addGroup(
                        layout
                            .createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addGroup(
                                layout
                                    .createSequentialGroup()
                                    .addGap(40, 40, 40)
                                    .addGroup(
                                        layout
                                            .createParallelGroup(
                                                javax.swing.GroupLayout.Alignment.LEADING, false)
                                            .addComponent(jLabel7)
                                            .addGroup(
                                                javax.swing.GroupLayout.Alignment.TRAILING,
                                                layout
                                                    .createSequentialGroup()
                                                    .addComponent(
                                                        menuoperaciones, 0, 1, Short.MAX_VALUE)
                                                    .addPreferredGap(
                                                        javax.swing.LayoutStyle.ComponentPlacement
                                                            .UNRELATED)
                                                    .addComponent(
                                                        calcular,
                                                        javax.swing.GroupLayout.PREFERRED_SIZE,
                                                        88,
                                                        javax.swing.GroupLayout.PREFERRED_SIZE)
                                                    .addPreferredGap(
                                                        javax.swing.LayoutStyle.ComponentPlacement
                                                            .RELATED)
                                                    .addComponent(jLabel5))
                                            .addGroup(
                                                layout
                                                    .createSequentialGroup()
                                                    .addGroup(
                                                        layout
                                                            .createParallelGroup(
                                                                javax.swing.GroupLayout.Alignment
                                                                    .LEADING)
                                                            .addComponent(jLabel1)
                                                            .addComponent(jLabel3)
                                                            .addComponent(
                                                                CodigoLibro,
                                                                javax.swing.GroupLayout
                                                                    .PREFERRED_SIZE,
                                                                138,
                                                                javax.swing.GroupLayout
                                                                    .PREFERRED_SIZE))
                                                    .addGap(63, 63, 63)
                                                    .addGroup(
                                                        layout
                                                            .createParallelGroup(
                                                                javax.swing.GroupLayout.Alignment
                                                                    .TRAILING)
                                                            .addComponent(
                                                                jLabel9,
                                                                javax.swing.GroupLayout.Alignment
                                                                    .LEADING)
                                                            .addComponent(
                                                                FechaSalida,
                                                                javax.swing.GroupLayout.Alignment
                                                                    .LEADING,
                                                                javax.swing.GroupLayout
                                                                    .PREFERRED_SIZE,
                                                                173,
                                                                javax.swing.GroupLayout
                                                                    .PREFERRED_SIZE))
                                                    .addPreferredGap(
                                                        javax.swing.LayoutStyle.ComponentPlacement
                                                            .RELATED,
                                                        javax.swing.GroupLayout.DEFAULT_SIZE,
                                                        Short.MAX_VALUE)
                                                    .addGroup(
                                                        layout
                                                            .createParallelGroup(
                                                                javax.swing.GroupLayout.Alignment
                                                                    .LEADING)
                                                            .addComponent(jLabel2)
                                                            .addComponent(
                                                                Cedula,
                                                                javax.swing.GroupLayout
                                                                    .PREFERRED_SIZE,
                                                                108,
                                                                javax.swing.GroupLayout
                                                                    .PREFERRED_SIZE)))
                                            .addGroup(
                                                layout
                                                    .createParallelGroup(
                                                        javax.swing.GroupLayout.Alignment.TRAILING)
                                                    .addComponent(
                                                        mostrar,
                                                        javax.swing.GroupLayout.PREFERRED_SIZE,
                                                        108,
                                                        javax.swing.GroupLayout.PREFERRED_SIZE)
                                                    .addGroup(
                                                        layout
                                                            .createSequentialGroup()
                                                            .addGroup(
                                                                layout
                                                                    .createParallelGroup(
                                                                        javax.swing.GroupLayout
                                                                            .Alignment.TRAILING)
                                                                    .addComponent(
                                                                        FechaMaximaDevolucion,
                                                                        javax.swing.GroupLayout
                                                                            .PREFERRED_SIZE,
                                                                        173,
                                                                        javax.swing.GroupLayout
                                                                            .PREFERRED_SIZE)
                                                                    .addGroup(
                                                                        layout
                                                                            .createParallelGroup(
                                                                                javax.swing
                                                                                    .GroupLayout
                                                                                    .Alignment
                                                                                    .LEADING)
                                                                            .addComponent(
                                                                                jScrollPane1,
                                                                                javax.swing
                                                                                    .GroupLayout
                                                                                    .PREFERRED_SIZE,
                                                                                374,
                                                                                javax.swing
                                                                                    .GroupLayout
                                                                                    .PREFERRED_SIZE)
                                                                            .addComponent(
                                                                                CodigoPrestamo,
                                                                                javax.swing
                                                                                    .GroupLayout
                                                                                    .PREFERRED_SIZE,
                                                                                138,
                                                                                javax.swing
                                                                                    .GroupLayout
                                                                                    .PREFERRED_SIZE)))
                                                            .addGroup(
                                                                layout
                                                                    .createParallelGroup(
                                                                        javax.swing.GroupLayout
                                                                            .Alignment.LEADING)
                                                                    .addGroup(
                                                                        layout
                                                                            .createSequentialGroup()
                                                                            .addGap(36, 36, 36)
                                                                            .addComponent(
                                                                                buscar,
                                                                                javax.swing
                                                                                    .GroupLayout
                                                                                    .PREFERRED_SIZE,
                                                                                108,
                                                                                javax.swing
                                                                                    .GroupLayout
                                                                                    .PREFERRED_SIZE))
                                                                    .addGroup(
                                                                        javax.swing.GroupLayout
                                                                            .Alignment.TRAILING,
                                                                        layout
                                                                            .createSequentialGroup()
                                                                            .addPreferredGap(
                                                                                javax.swing
                                                                                    .LayoutStyle
                                                                                    .ComponentPlacement
                                                                                    .RELATED)
                                                                            .addGroup(
                                                                                layout
                                                                                    .createParallelGroup(
                                                                                        javax.swing
                                                                                            .GroupLayout
                                                                                            .Alignment
                                                                                            .LEADING)
                                                                                    .addComponent(
                                                                                        jButton6,
                                                                                        javax.swing
                                                                                            .GroupLayout
                                                                                            .Alignment
                                                                                            .TRAILING,
                                                                                        javax.swing
                                                                                            .GroupLayout
                                                                                            .PREFERRED_SIZE,
                                                                                        108,
                                                                                        javax.swing
                                                                                            .GroupLayout
                                                                                            .PREFERRED_SIZE)
                                                                                    .addComponent(
                                                                                        salir,
                                                                                        javax.swing
                                                                                            .GroupLayout
                                                                                            .Alignment
                                                                                            .TRAILING,
                                                                                        javax.swing
                                                                                            .GroupLayout
                                                                                            .PREFERRED_SIZE,
                                                                                        108,
                                                                                        javax.swing
                                                                                            .GroupLayout
                                                                                            .PREFERRED_SIZE))))))
                                            .addComponent(
                                                panel,
                                                javax.swing.GroupLayout.PREFERRED_SIZE,
                                                510,
                                                javax.swing.GroupLayout.PREFERRED_SIZE)))
                            .addGroup(
                                layout
                                    .createSequentialGroup()
                                    .addGap(227, 227, 227)
                                    .addComponent(jLabel6)))
                    .addContainerGap(44, Short.MAX_VALUE)));
    layout.setVerticalGroup(
        layout
            .createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(
                layout
                    .createSequentialGroup()
                    .addGroup(
                        layout
                            .createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addGroup(
                                javax.swing.GroupLayout.Alignment.TRAILING,
                                layout
                                    .createSequentialGroup()
                                    .addComponent(jLabel6)
                                    .addGap(18, 18, 18)
                                    .addGroup(
                                        layout
                                            .createParallelGroup(
                                                javax.swing.GroupLayout.Alignment.LEADING)
                                            .addComponent(jLabel2)
                                            .addComponent(jLabel8))
                                    .addPreferredGap(
                                        javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                    .addGroup(
                                        layout
                                            .createParallelGroup(
                                                javax.swing.GroupLayout.Alignment.BASELINE)
                                            .addComponent(
                                                FechaSalida,
                                                javax.swing.GroupLayout.PREFERRED_SIZE,
                                                javax.swing.GroupLayout.DEFAULT_SIZE,
                                                javax.swing.GroupLayout.PREFERRED_SIZE)
                                            .addComponent(
                                                Cedula,
                                                javax.swing.GroupLayout.PREFERRED_SIZE,
                                                javax.swing.GroupLayout.DEFAULT_SIZE,
                                                javax.swing.GroupLayout.PREFERRED_SIZE))
                                    .addGap(16, 27, Short.MAX_VALUE))
                            .addGroup(
                                layout
                                    .createSequentialGroup()
                                    .addGap(48, 48, 48)
                                    .addComponent(jLabel1)
                                    .addPreferredGap(
                                        javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                    .addComponent(
                                        CodigoPrestamo,
                                        javax.swing.GroupLayout.PREFERRED_SIZE,
                                        javax.swing.GroupLayout.DEFAULT_SIZE,
                                        javax.swing.GroupLayout.PREFERRED_SIZE)
                                    .addGap(0, 0, Short.MAX_VALUE)))
                    .addGroup(
                        layout
                            .createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                            .addComponent(jLabel9)
                            .addComponent(jLabel3))
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                    .addGroup(
                        layout
                            .createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                            .addComponent(
                                CodigoLibro,
                                javax.swing.GroupLayout.PREFERRED_SIZE,
                                javax.swing.GroupLayout.DEFAULT_SIZE,
                                javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(
                                FechaMaximaDevolucion,
                                javax.swing.GroupLayout.PREFERRED_SIZE,
                                javax.swing.GroupLayout.DEFAULT_SIZE,
                                javax.swing.GroupLayout.PREFERRED_SIZE))
                    .addGap(18, 18, 18)
                    .addGroup(
                        layout
                            .createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                            .addGroup(
                                layout
                                    .createSequentialGroup()
                                    .addGap(10, 10, 10)
                                    .addComponent(buscar)
                                    .addGap(58, 58, 58)
                                    .addComponent(mostrar)
                                    .addGap(18, 18, 18)
                                    .addComponent(jButton6)
                                    .addGap(18, 18, 18)
                                    .addComponent(salir))
                            .addComponent(jScrollPane1))
                    .addGap(18, 18, 18)
                    .addGroup(
                        layout
                            .createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                            .addComponent(
                                menuoperaciones,
                                javax.swing.GroupLayout.PREFERRED_SIZE,
                                javax.swing.GroupLayout.DEFAULT_SIZE,
                                javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(calcular)
                            .addComponent(
                                jLabel5,
                                javax.swing.GroupLayout.PREFERRED_SIZE,
                                23,
                                javax.swing.GroupLayout.PREFERRED_SIZE))
                    .addGap(7, 7, 7)
                    .addComponent(jLabel7)
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                    .addComponent(
                        panel,
                        javax.swing.GroupLayout.PREFERRED_SIZE,
                        112,
                        javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)));

    pack();
  } // </editor-fold>//GEN-END:initComponents