ERROR "class ... does not have a main method

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ERROR "class ... does not have a main method

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#1 by (0 votes)
#2 by (0 votes)

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I have a small problem with this error ... at the moment of throwing it indicates to me that I do not have a method ... which if I have, the truth is that I do not find the error, I need your help I leave the code for you if you can help me

package sistemalaboratorio;

import claseConectar.conectar;
import java.sql.*;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JOptionPane;

/**
 *
 * @author ESTACION 4
 */
public class Login extends javax.swing.JPanel {


        void acceder(String usuario, String pass)
    {
        String cap="";
       String sql="SELECT * FROM usuario WHERE nick='"+usuario+"' && password='"+pass+"'";
        try {
            Statement st = cn.createStatement();
            ResultSet rs = st.executeQuery(sql);
            while(rs.next())
            {
                cap=rs.getString("tipousuario");
            }
            if(cap.equals("Administrador"))
            {
                  this.setVisible(false);
                    JOptionPane.showMessageDialog(null, "Bienvenido");
            //         ventanaadmin ingreso = new ventanaadmin();
            //        ingreso.setVisible(true);
            //        ingreso.pack();
            //         ventanaadmin.lblusu.setText(usuario);


            }
            if(cap.equals("Invitado"))
            {
            this.setVisible(false);
                    JOptionPane.showMessageDialog(null, "Bienvenido");
             //        ventanacliente ingresos = new ventanacliente();
              //      ingresos.setVisible(true);
             //       ingresos.pack();
             //        ventanacliente.lblconectado.setText(usuario);
            }
            if((!cap.equals("Administrador"))&& (!cap.equals("Invitado")))
            {
                JOptionPane.showMessageDialog(this, "No existe sus datos");
            }
        } catch (SQLException ex) {
            Logger.getLogger(Login.class.getName()).log(Level.SEVERE, null, ex);
        }

        }
    /**
     * Creates new form Login
     */
    public Login() {
        initComponents();
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jPanel2 = new javax.swing.JPanel();
        jLabel2 = new javax.swing.JLabel();
        jLabel3 = new javax.swing.JLabel();
        lblPassword = new javax.swing.JLabel();
        btningresar = new javax.swing.JButton();
        txtPassword = new javax.swing.JPasswordField();
        txtusuario = new javax.swing.JTextField();
        jPanel1 = new javax.swing.JPanel();
        jLabel1 = new javax.swing.JLabel();

        jPanel2.setBackground(new java.awt.Color(238, 232, 232));
        jPanel2.setBorder(new javax.swing.border.SoftBevelBorder(javax.swing.border.BevelBorder.RAISED));

        jLabel2.setFont(new java.awt.Font("Tahoma", 0, 18)); // NOI18N
        jLabel2.setText("USUARIO");

        jLabel3.setFont(new java.awt.Font("Tahoma", 0, 18)); // NOI18N
        jLabel3.setText("CONTRASEÑA");

        lblPassword.setBackground(new java.awt.Color(0, 153, 255));
        lblPassword.setForeground(new java.awt.Color(0, 204, 255));
        lblPassword.setText("Recordar Contraseña");

        btningresar.setText("INGRESAR");
        btningresar.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btningresarActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout jPanel2Layout = new javax.swing.GroupLayout(jPanel2);
        jPanel2.setLayout(jPanel2Layout);
        jPanel2Layout.setHorizontalGroup(
            jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel2Layout.createSequentialGroup()
                .addGap(251, 251, 251)
                .addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(jLabel3)
                    .addComponent(jLabel2, javax.swing.GroupLayout.PREFERRED_SIZE, 112, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addContainerGap(531, Short.MAX_VALUE))
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel2Layout.createSequentialGroup()
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(lblPassword, javax.swing.GroupLayout.PREFERRED_SIZE, 200, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(btningresar, javax.swing.GroupLayout.PREFERRED_SIZE, 140, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(59, 59, 59))
        );
        jPanel2Layout.setVerticalGroup(
            jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel2Layout.createSequentialGroup()
                .addGap(207, 207, 207)
                .addComponent(jLabel2, javax.swing.GroupLayout.PREFERRED_SIZE, 33, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(57, 57, 57)
                .addComponent(jLabel3)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 57, Short.MAX_VALUE)
                .addComponent(btningresar)
                .addGap(18, 18, 18)
                .addComponent(lblPassword)
                .addGap(49, 49, 49))
        );

        txtPassword.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                txtPasswordActionPerformed(evt);
            }
        });

        jPanel1.setBackground(new java.awt.Color(0, 0, 0));

        jLabel1.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        jLabel1.setForeground(new java.awt.Color(255, 255, 255));
        jLabel1.setText("DataLab (LIMS) Software Login");
        jLabel1.setHorizontalTextPosition(javax.swing.SwingConstants.CENTER);

        javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
        jPanel1.setLayout(jPanel1Layout);
        jPanel1Layout.setHorizontalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
                .addContainerGap(216, Short.MAX_VALUE)
                .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 397, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(197, 197, 197))
        );
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel1Layout.createSequentialGroup()
                .addGap(28, 28, 28)
                .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 39, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(33, Short.MAX_VALUE))
        );

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(this);
        this.setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 900, Short.MAX_VALUE)
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(layout.createSequentialGroup()
                    .addGap(0, 0, Short.MAX_VALUE)
                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                        .addGroup(layout.createSequentialGroup()
                            .addGap(480, 480, 480)
                            .addComponent(txtPassword, javax.swing.GroupLayout.PREFERRED_SIZE, 158, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addGroup(layout.createSequentialGroup()
                            .addGap(480, 480, 480)
                            .addComponent(txtusuario, javax.swing.GroupLayout.PREFERRED_SIZE, 158, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addGroup(layout.createSequentialGroup()
                            .addGap(50, 50, 50)
                            .addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addComponent(jPanel2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                    .addGap(0, 0, Short.MAX_VALUE)))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 490, Short.MAX_VALUE)
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(layout.createSequentialGroup()
                    .addGap(0, 0, Short.MAX_VALUE)
                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                        .addGroup(layout.createSequentialGroup()
                            .addGap(290, 290, 290)
                            .addComponent(txtPassword, javax.swing.GroupLayout.PREFERRED_SIZE, 37, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addGroup(layout.createSequentialGroup()
                            .addGap(210, 210, 210)
                            .addComponent(txtusuario, javax.swing.GroupLayout.PREFERRED_SIZE, 33, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addGroup(layout.createSequentialGroup()
                            .addGap(70, 70, 70)
                            .addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addComponent(jPanel2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                    .addGap(0, 0, Short.MAX_VALUE)))
        );
    }// </editor-fold>                        

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

    private void btningresarActionPerformed(java.awt.event.ActionEvent evt) {                                            

                String usu=txtusuario.getText();
    String pas=new String(txtPassword.getPassword());
    acceder(usu, pas);// TODO add your handling code here:
    }                                           


    // Variables declaration - do not modify                     
    private javax.swing.JButton btningresar;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JLabel jLabel3;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JPanel jPanel2;
    private javax.swing.JLabel lblPassword;
    private javax.swing.JPasswordField txtPassword;
    private javax.swing.JTextField txtusuario;
    // End of variables declaration                   
conectar cc= new conectar();
Connection cn= cc.conexion();
}

java poo netbeans

asked by Juan Pablo 07.05.2018 в 20:38

source

2 answers

0

In java the starting point is the Main, from there is where you compile your code. The Main method is:

public static void Clase(String[] args){
   //Aqui es donde se coloca el codigo que iniciara tu sistema.
}

Good luck ...

answered by 07.05.2018 в 22:06

Problems with webpack Problem with elifs and local variables

score 0 · Accepted Answer

This error indicates that a main() method has not been defined in your package or in your class. I do not see it and to fix it I suggest you include it.

Every application made in Java needs a main() method within the class that starts to run the program. This method is the one that is executed when an application of Java is executed, therefore there you must define what your program in Java will do until finished.

The main() method must be contained in the initiating class that must call as the source file in which it is declared. This is the structure for the declaration of a main() method:

public class NombreFichero
{
    public static void main (String[] args)
    {
       // Aquí incluyes las instrucciones que tu programa ejecutará.
    }
}

You replace NombreFichero with the name of the file that will contain the initializing class that will contain your method main() .

In your case you must include the main() method in your class Login .