MdiForm centralizado no NetBeans

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package Telas;

import java.awt.Dimension;
import java.awt.Toolkit;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JInternalFrame;

/**
 *
 * @author Usuario
 */
public class MdiForm extends javax.swing.JFrame {

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

        jMenu1 = new javax.swing.JMenu();
        jMenu2 = new javax.swing.JMenu();
        desktopPane = new javax.swing.JDesktopPane();
        menuBar = new javax.swing.JMenuBar();
        jMenu3 = new javax.swing.JMenu();
        jMenuItem2 = new javax.swing.JMenuItem();
        jMenuItem1 = new javax.swing.JMenuItem();

        jMenu1.setText("jMenu1");

        jMenu2.setText("jMenu2");

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setAlwaysOnTop(true);

        menuBar.setBorder(null);
        menuBar.setCursor(new java.awt.Cursor(java.awt.Cursor.DEFAULT_CURSOR));
        menuBar.setFont(new java.awt.Font("Tahoma", 0, 12)); // NOI18N
        menuBar.setName("");
        menuBar.addAncestorListener(new javax.swing.event.AncestorListener() {
            public void ancestorMoved(javax.swing.event.AncestorEvent evt) {
            }
            public void ancestorAdded(javax.swing.event.AncestorEvent evt) {
                menuBarAncestorAdded(evt);
            }
            public void ancestorRemoved(javax.swing.event.AncestorEvent evt) {
            }
        });

        jMenu3.setText("Forms");

        jMenuItem2.setText("Form1");
        jMenuItem2.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jMenuItem2ActionPerformed(evt);
            }
        });
        jMenu3.add(jMenuItem2);

        jMenuItem1.setText("Form2");
        jMenuItem1.setToolTipText("");
        jMenuItem1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jMenuItem1ActionPerformed(evt);
            }
        });
        jMenu3.add(jMenuItem1);

        menuBar.add(jMenu3);

        setJMenuBar(menuBar);

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(desktopPane, javax.swing.GroupLayout.DEFAULT_SIZE, 800, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(desktopPane, javax.swing.GroupLayout.DEFAULT_SIZE, 600, Short.MAX_VALUE)
        );

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

    private void menuBarAncestorAdded(javax.swing.event.AncestorEvent evt) {                                      
        // TODO add your handling code here:
    }                                     

    public static void centralizar(JInternalFrame fr){   
      Dimension d = fr.getDesktopPane().getSize();   
      fr.setLocation((d.width - fr.getSize().width) / 2, (d.height - fr.getSize().height) / 2);      
   } 
    
    
    
    private void jMenuItem2ActionPerformed(java.awt.event.ActionEvent evt) {                                           
        Frame1 frm1;
        try {
            frm1 = new Frame1();
            desktopPane.add(frm1);
        frm1.setVisible(true);
        centralizar(frm1); 
        } catch (ClassNotFoundException ex) {
            Logger.getLogger(MdiForm.class.getName()).log(Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            Logger.getLogger(MdiForm.class.getName()).log(Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            Logger.getLogger(MdiForm.class.getName()).log(Level.SEVERE, null, ex);
        }
        
    }                                          

    private void jMenuItem1ActionPerformed(java.awt.event.ActionEvent evt) {                                           
        // TODO add your handling code here:
    }                                          

    /**
     * @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(MdiForm.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(MdiForm.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(MdiForm.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(MdiForm.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 MdiForm().setVisible(true);
                
            }
        });
    }
    // Variables declaration - do not modify
    private javax.swing.JDesktopPane desktopPane;
    private javax.swing.JMenu jMenu1;
    private javax.swing.JMenu jMenu2;
    private javax.swing.JMenu jMenu3;
    private javax.swing.JMenuItem jMenuItem1;
    private javax.swing.JMenuItem jMenuItem2;
    private javax.swing.JMenuBar menuBar;
    // End of variables declaration
}