how to make a class jframe be main if I have previously defined the main class?

Well what I have is the following, a class main that I have put a connection that will take my jframe , but once done the main I started to create the interface, as I do so that when execute the interface appears, which was the second thing I did, that is, to pass the main of the test to the interface.

package conexion;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;

public class test {

    public static void main(String[] args) {
        try {

            conexion c = new conexion();

            c.borrarPersona("123");
            c.insertarPersona("13123", "paquirronti", "quenodise", "ala puediera", "notatuloco", "nulllazo");
            c.mostrar_personas();

        } catch (Exception e) {

        }

    }
}

public class INTERFAZ extends javax.swing.JFrame {

/**
 * Creates new form INTERFAZ
 */
public INTERFAZ() {
    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() {

    choice1 = new java.awt.Choice();
    jProgressBar1 = new javax.swing.JProgressBar();
    jPasswordField1 = new javax.swing.JPasswordField();
    jFormattedTextField1 = new javax.swing.JFormattedTextField();
    jSlider1 = new javax.swing.JSlider();
    jColorChooser1 = new javax.swing.JColorChooser();
    jSpinner1 = new javax.swing.JSpinner();
    jSpinner2 = new javax.swing.JSpinner();
    jCheckBox1 = new javax.swing.JCheckBox();
    jScrollPane1 = new javax.swing.JScrollPane();
    label = new java.awt.Label();
    label1 = new java.awt.Label();
    boton_borrar = new javax.swing.JButton();
    boton_añadir = new javax.swing.JButton();
    jScrollPane2 = new javax.swing.JScrollPane();
    lista_personas = new javax.swing.JList();
    jLabel1 = new javax.swing.JLabel();
    jTextField1 = new javax.swing.JTextField();
    jTextField2 = new javax.swing.JTextField();
    jTextField3 = new javax.swing.JTextField();
    jTextField4 = new javax.swing.JTextField();
    jLabel2 = new javax.swing.JLabel();
    boton_limpiar = new javax.swing.JButton();
    jTextField5 = new javax.swing.JTextField();
    jTextField6 = new javax.swing.JTextField();

    jPasswordField1.setText("jPasswordField1");

    jFormattedTextField1.setText("jFormattedTextField1");

    jCheckBox1.setText("jCheckBox1");

    label.setText("label1");

    label1.setText("label1");

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
    setBackground(new java.awt.Color(204, 204, 255));

    boton_borrar.setBackground(new java.awt.Color(255, 51, 51));
    boton_borrar.setText("Borrar");

    boton_añadir.setBackground(java.awt.Color.green);
    boton_añadir.setText("Añadir");

    jScrollPane2.setViewportView(lista_personas);

    jLabel1.setText("DNI:");

    jLabel2.setText("Personas");

    boton_limpiar.setBackground(java.awt.Color.white);
    boton_limpiar.setText("Limpiar");

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
            .addGap(28, 28, 28)
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                .addGroup(layout.createSequentialGroup()
                    .addComponent(jScrollPane2, javax.swing.GroupLayout.PREFERRED_SIZE, 167, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 59, Short.MAX_VALUE)
                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                        .addGroup(layout.createSequentialGroup()
                            .addComponent(jLabel1)
                            .addGap(18, 18, 18)
                            .addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, 101, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, 101, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addComponent(jTextField3, javax.swing.GroupLayout.PREFERRED_SIZE, 101, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addComponent(jTextField4, javax.swing.GroupLayout.PREFERRED_SIZE, 101, javax.swing.GroupLayout.PREFERRED_SIZE))
                    .addGap(73, 73, 73)
                    .addComponent(boton_añadir)
                    .addGap(46, 46, 46))
                .addGroup(layout.createSequentialGroup()
                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                        .addGroup(layout.createSequentialGroup()
                            .addComponent(boton_limpiar)
                            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                            .addComponent(jTextField6, javax.swing.GroupLayout.PREFERRED_SIZE, 101, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addGroup(layout.createSequentialGroup()
                            .addGap(0, 0, Short.MAX_VALUE)
                            .addComponent(jTextField5, javax.swing.GroupLayout.PREFERRED_SIZE, 101, javax.swing.GroupLayout.PREFERRED_SIZE)))
                    .addGap(82, 82, 82)
                    .addComponent(boton_borrar)
                    .addGap(38, 38, 38))))
        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(96, 96, 96)
                .addComponent(jLabel2)
                .addContainerGap(429, Short.MAX_VALUE)))
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(layout.createSequentialGroup()
                    .addGap(28, 28, 28)
                    .addComponent(boton_añadir)
                    .addGap(23, 23, 23))
                .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                    .addContainerGap()
                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                        .addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addComponent(jLabel1))
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)))
            .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addGap(18, 18, 18)
            .addComponent(jTextField3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addGap(18, 18, 18)
            .addComponent(jTextField4, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addGap(18, 18, 18)
            .addComponent(jTextField5, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addGap(18, 18, 18)
            .addComponent(jTextField6, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 82, Short.MAX_VALUE)
            .addComponent(boton_borrar)
            .addGap(14, 14, 14))
        .addGroup(layout.createSequentialGroup()
            .addGap(55, 55, 55)
            .addComponent(jScrollPane2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
            .addComponent(boton_limpiar)
            .addContainerGap())
        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(31, 31, 31)
                .addComponent(jLabel2)
                .addContainerGap(368, Short.MAX_VALUE)))
    );

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

/**
 * @param args the command line arguments
 */
public static void main(String args[]) {
    /* Set the Nimbus look and feel */
    //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
    /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
     * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
     */
    try {
        for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
            if ("Nimbus".equals(info.getName())) {
                javax.swing.UIManager.setLookAndFeel(info.getClassName());
                break;
            }
        }
    } catch (ClassNotFoundException ex) {
        java.util.logging.Logger.getLogger(INTERFAZ.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (InstantiationException ex) {
        java.util.logging.Logger.getLogger(INTERFAZ.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (IllegalAccessException ex) {
        java.util.logging.Logger.getLogger(INTERFAZ.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (javax.swing.UnsupportedLookAndFeelException ex) {
        java.util.logging.Logger.getLogger(INTERFAZ.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 INTERFAZ().setVisible(true);
        }
    });
}

// Variables declaration - do not modify                     
private javax.swing.JButton boton_añadir;
private javax.swing.JButton boton_borrar;
private javax.swing.JButton boton_limpiar;
private java.awt.Choice choice1;
private javax.swing.JCheckBox jCheckBox1;
private javax.swing.JColorChooser jColorChooser1;
private javax.swing.JFormattedTextField jFormattedTextField1;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JPasswordField jPasswordField1;
private javax.swing.JProgressBar jProgressBar1;
private javax.swing.JScrollPane jScrollPane1;
private javax.swing.JScrollPane jScrollPane2;
private javax.swing.JSlider jSlider1;
private javax.swing.JSpinner jSpinner1;
private javax.swing.JSpinner jSpinner2;
private javax.swing.JTextField jTextField1;
private javax.swing.JTextField jTextField2;
private javax.swing.JTextField jTextField3;
private javax.swing.JTextField jTextField4;
private javax.swing.JTextField jTextField5;
private javax.swing.JTextField jTextField6;
private java.awt.Label label;
private java.awt.Label label1;
private javax.swing.JList lista_personas;
// End of variables declaration                   
}