private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_jButton1ActionPerformed
        // TODO add your handling code here:
        if(st.equalsIgnoreCase("Mas")){
            if(jList1.getSelectedValue() != null){
                for(int i = 0; i < meses.size();i++){
                    if(jList1.getSelectedValue().equals(meses.get(i))){
                        dispose();
                        new Formas().Fecha(meses.get(i+1));
                        break;
                    }                    
                }
            }else{
                JOptionPane.showMessageDialog(this,"Debe de seleccionar una fecha");
            }
        }else{
            if(jList1.getSelectedValue() != null){
                for(int i = 0; i < meses.size();i++){
                    if(jList1.getSelectedValue().equals(meses.get(i))){
                        dispose();
                        new Formas().FechaM(meses.get(i+1));
                        break;
                    }                    
                }
            }else{
                JOptionPane.showMessageDialog(this,"Debe de seleccionar una fecha");
            }
        }
    }//GEN-LAST:event_jButton1ActionPerformed