Dynamically Add Components to a JDialog

Question

I am having trouble adding JComponents to a JDialog when the user clicks a button on the JDialog. Basically I want it to look like this:

Then, when the user clicks "Add New Field" I want it to look like this:

I cannot seem to get the dialog to add the new JLabel or JTextField. Can anyone point me in the right direction?

EDIT: This is the action for the "Add New Field" button (Just trying a label now).

@Action public void addNewField() {     Container contentPane = getContentPane();     JLabel label = new JLabel ("welkom");     contentPane.add(label, BorderLayout.CENTER); } 

SOLUTION:

I used mre's solution and got it to work. Here is my final function:

@Action public void addNewField() {     System.out.println("New Field...");     Container contentPane = getContentPane();     JLabel label = new JLabel ("welcome");     label.setBounds(10,10,100,10); //some random value that I know is in my dialog     contentPane.add(label);      contentPane.validate();     contentPane.repaint();     this.pack(); } 

Another one of my problems is that I am using a "Free Design" layout in NetBeans, which meant that my label was probably in some weird position rather than being in the bounds of my dialog (just a guess). I solved this problem with label.setBounds() so that it showed exactly where I wanted it to.

Answer 1

When dynamically adding/removing components from a container, it's necessary to invoke revalidate()/validate() and repaint() afterward. The former will force the container to layout its components again and the latter will remove any visual "artifacts".

Answer 2

to avoiding any further discusion about required/non-required any of Methods ...

notice: for adds/removes JComponents (simple structured just in one Row/Column and with same Size on Screen) is sufficient just action JFrame.pack(),

but for most complete GUI layed by some of standard Swing LayoutManagers is required usage of

revalidate(); repaint(); // required in most of cases  

example for one Column

import java.awt.Color; import java.awt.Dimension; import java.awt.GridLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JButton; import javax.swing.JCheckBox; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.border.LineBorder;  public class AddComponentsAtRuntime {      private JFrame f;     private JPanel panel;     private JCheckBox checkValidate, checkReValidate, checkRepaint, checkPack;      public AddComponentsAtRuntime() {         JButton b = new JButton();         b.setBackground(Color.red);         b.setBorder(new LineBorder(Color.black, 2));         b.setPreferredSize(new Dimension(600, 10));         panel = new JPanel(new GridLayout(0, 1));         panel.add(b);         f = new JFrame();         f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);         f.add(panel, "Center");         f.add(getCheckBoxPanel(), "South");         f.setLocation(200, 200);         f.pack();         f.setVisible(true);     }      private JPanel getCheckBoxPanel() {         checkValidate = new JCheckBox("validate");         checkValidate.setSelected(false);         checkReValidate = new JCheckBox("revalidate");         checkReValidate.setSelected(false);         checkRepaint = new JCheckBox("repaint");         checkRepaint.setSelected(false);         checkPack = new JCheckBox("pack");         checkPack.setSelected(false);         JButton addComp = new JButton("Add New One");         addComp.addActionListener(new ActionListener() {              @Override             public void actionPerformed(ActionEvent e) {                 JButton b = new JButton();                 b.setBackground(Color.red);                 b.setBorder(new LineBorder(Color.black, 2));                 b.setPreferredSize(new Dimension(600, 10));                 panel.add(b);                 makeChange();                 System.out.println(" Components Count after Adds :" + panel.getComponentCount());             }         });         JButton removeComp = new JButton("Remove One");         removeComp.addActionListener(new ActionListener() {              @Override             public void actionPerformed(ActionEvent e) {                 int count = panel.getComponentCount();                 if (count > 0) {                     panel.remove(0);                 }                 makeChange();                 System.out.println(" Components Count after Removes :" + panel.getComponentCount());             }         });         JPanel panel2 = new JPanel();         panel2.add(checkValidate);         panel2.add(checkReValidate);         panel2.add(checkRepaint);         panel2.add(checkPack);         panel2.add(addComp);         panel2.add(removeComp);         return panel2;     }      private void makeChange() {         if (checkValidate.isSelected()) {             panel.validate();         }         if (checkReValidate.isSelected()) {             panel.revalidate();         }         if (checkRepaint.isSelected()) {             panel.repaint();         }         if (checkPack.isSelected()) {             f.pack();         }     }      public static void main(String[] args) {         AddComponentsAtRuntime makingChanges = new AddComponentsAtRuntime();     } }