Программное добавление компонента. NetBeans.

    
public NewJFrame() {
        initComponents();
        jPanel1.add(new JButton("My Button"));
        jPanel1.getParent().validate();
    }

package ru.skipy.tests;
 
import javax.swing.*;
import java.awt.*;
 
/**
 * LayoutSample1Test
 *
 * @author Eugene Matyushkin aka Skipy
 * @since 20.01.2011
 */
public class LayoutSample1Test extends JFrame {
 
    LayoutSample1Test(){
        super("Layout sample 1");
        JPanel p = new JPanel(new GridBagLayout());
        p.setBorder(BorderFactory.createEmptyBorder(5,5,5,5));
        p.setBackground(Color.white);
        JCheckBox cb = new JCheckBox("Check me");
        cb.setOpaque(false);
        final JTextField tf = new JTextField();
        tf.setBorder(null);
        tf.setBackground(new Color(192,192,255));
        JButton btn = new JButton("Click me");
        p.add(cb, new GridBagConstraints(0,0,1,1,1,0,GridBagConstraints.WEST, GridBagConstraints.HORIZONTAL, new Insets(0,0,0,5), 0,0));
 
        p.add(tf, new GridBagConstraints(1,0,1,1,1,0,GridBagConstraints.WEST, GridBagConstraints.HORIZONTAL, new Insets(0,0,0,5), 0,0));
//        p.add(tf);
 
        p.add(btn, new GridBagConstraints(2,0,1,1,1,0,GridBagConstraints.WEST, GridBagConstraints.HORIZONTAL, new Insets(0,0,0,5), 0,0));
        setContentPane(p);
        setSize(400, 100);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setLocationRelativeTo(null);
    }
 
    public static void main(String[] args) {
        new LayoutSample1Test().setVisible(true);
    }
}

tf.addFocusListener(new FocusListener(){
    @Override
    public void focusGained(FocusEvent e) {
        System.out.println("Focus gained: "+tf.getSize()+", "+tf.getLocation());
    }
 
    @Override
    public void focusLost(FocusEvent e) {
        System.out.println("Focus lost: "+tf.getSize()+", "+tf.getLocation());
    }
});

final JTextField tf = new JTextField("я тут");

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
 
/*
 * NewJFrame2.java
 *
 * Created on 20.01.2011, 15:54:14
 */
 
package ru.skipy.tests.ui;
 
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import javax.swing.JTextField;
 
/**
 *
 * @author Eugene Matyushkin aka Skipy
 */
public class NewJFrame2 extends javax.swing.JFrame {
 
    /** Creates new form NewJFrame2 */
    public NewJFrame2() {
        initComponents();
        final JTextField tf = new JTextField("Some text");
        add(tf);
        pack();
        tf.addFocusListener(new FocusListener(){
            public void focusGained(FocusEvent e) {
                System.out.println("Focus gained: "+tf.getSize()+", "+tf.getLocation());
            }
 
            public void focusLost(FocusEvent e) {
                System.out.println("Focus lost: "+tf.getSize()+", "+tf.getLocation());
            }
        });
 
    }
 
    /** 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() {
 
        jLabel1 = new javax.swing.JLabel();
        jTextField1 = new javax.swing.JTextField();
        jButton1 = new javax.swing.JButton();
 
        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
 
        jLabel1.setText("jLabel1");
 
        jTextField1.setText("jTextField1");
 
        jButton1.setText("jButton1");
 
        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(32, 32, 32)
                .addComponent(jLabel1)
                .addGap(48, 48, 48)
                .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(48, 48, 48)
                .addComponent(jButton1)
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(46, 46, 46)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel1)
                    .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jButton1))
                .addContainerGap(23, Short.MAX_VALUE))
        );
 
        pack();
    }// </editor-fold>
 
    /**
    * @param args the command line arguments
    */
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new NewJFrame2().setVisible(true);
            }
        });
    }
 
    // Variables declaration - do not modify
    private javax.swing.JButton jButton1;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JTextField jTextField1;
    // End of variables declaration
 
}