To create my GUI I created a number of subclasses of JPanel, each of those solving a specific layout problem.
The first is the AltBoxLayout_JPanel, inspired by the answer to a question I posed time ago (link: Setting the height of a JTextFrame): it simply is a couple of JPanels nestled one within the other, the inner one with a BoxLayout to distribute the components in the preferred way, the outer one with a BorderLayout to squeeze the components to their minimal dimension.
The second is the Fieldset, inspired by the HTML tag with the same name: again it is made by two nestled JPanels, the outer one with a TitleBorder, the inner one that is given in the constructor and whose purpose is to set up the layout inside the Fieldset zone.
I tested those two specialized components separately, with good results, and was satisfied by them. Recently I needed to use them both: I wanted a JButton and a JTextArea to be displayed one over the other without being artificially expanded (i.e. inside a AltBoxLayout_JPanel), and surrounded by a border (i.e. the AltBoxLayout_JPanel inside a Fieldset). Since all of my components were already tested, I was sure it would go well.
It didn't.
Somehow my JButton is not visible anymore. I know it is there (I checked) and I assume it is covered by the JTextArea, but I have no further information. Below is my code.
Any help in rescuing my JButton would be really appreciated!
public class StackOverflowQuestion extends JFrame {
private static final long serialVersionUID = -5644282466098799568L;
private JPanel contentPanel;
// Display area
private Fieldset fieldset;
private JButton button;
private JTextArea jTextArea;
/**
* Create the frame.
*/
public StackOverflowQuestion() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 300, 140);
contentPanel = new JPanel();
contentPanel.setBorder(new EmptyBorder(5, 5, 5, 5));
contentPanel.setLayout(new BorderLayout(0, 0));
setContentPane(contentPanel);
// Testing new components
// JPanel fieldsetLayoutPanel = new JPanel();
// BoxLayout fieldsetLayout = new BoxLayout(fieldsetLayoutPanel, BoxLayout.PAGE_AXIS);
// fieldsetLayoutPanel.setLayout(fieldsetLayout);
JPanel fieldsetLayoutPanel_2 = new AltBoxLayout_JPanel(BoxLayout.PAGE_AXIS);
this.fieldset = new Fieldset("Fieldset title", fieldsetLayoutPanel_2, null);
this.button = new JButton("Button text");
this.jTextArea = new JTextArea("JTextArea here!");
this.jTextArea.setRows(5);
this.jTextArea.setColumns(20);
this.button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
System.out.println("Action executed: " + arg0.toString());
}});
fieldset.add(button);
fieldset.add(jTextArea);
contentPanel.add(fieldset);
System.out.println("Analysis of the components of the contentPanel:");
analyzeLayoutsOfComponentAndSubComponents(contentPanel, 0);
pack();
}
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
StackOverflowQuestion frame = new StackOverflowQuestion();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/** A method that studies the {@link JPanel} and its sub-{@link JPanel}s, iterating through all the component tree.
*
* @param c
* @param tab
*/
public static void analyzeLayoutsOfComponentAndSubComponents(JPanel c, int tab) {
System.out.println(repeatChar('\t', tab) + c.toString());
for(int i=0 ; i<c.getComponentCount() ; i++)
if( c.getComponent(i) instanceof JPanel )
analyzeLayoutsOfComponentAndSubComponents( (JPanel)c.getComponent(i), tab+1 );
}
public static String repeatChar(char c, int tab) {
StringBuffer support = new StringBuffer();
for(int i=0 ; i<tab ; i++) support.append(c);
return support.toString();
}
public class Fieldset extends JPanel {
private static final long serialVersionUID = -1464052286624448783L;
/** The {@link Border} of {@code this} {@link Fieldset}. */
private Border border;
/** The {@link JPanel} responsible for the layout management. */
public JPanel layoutPanel;
/** Creates a new {@link Fieldset}.
*
* @param colorBorder The {@link Color} of the border. If {@code null}, {@code Color.BLACK} is chosen.
*
*/
public Fieldset(String titleFieldset, JPanel panel, Color colorBorder) {
super();
this.border = new TitledBorder(new LineBorder(colorBorder == null ? Color.BLACK : colorBorder), titleFieldset);
this.setBorder(border);
this.layoutPanel = panel;
super.add(layoutPanel);
}
public Component add(Component component) {
this.layoutPanel.add(component);
return component;
}
}
public class AltBoxLayout_JPanel extends JPanel {
private static final long serialVersionUID = -8204033141468207723L;
private JPanel layoutPanel;
/** Creates a new {@link AltBoxLayout_JPanel}.
*
* @param axisOrientation A constant from the {@link BoxLayout} class representing the chosen insertion axis.
*/
public AltBoxLayout_JPanel(int axisOrientation) {
// ===== INNER PANEL =====
this.layoutPanel = new JPanel(); //This is the nested panel
layoutPanel.setLayout(new BoxLayout(layoutPanel, axisOrientation));
// ===== OUTER PANEL =====
this.setLayout(new BorderLayout());
this.add(layoutPanel, BorderLayout.PAGE_START);
System.out.println("Analysis of the components of the AltBoxLayout_JPanel:");
analyzeLayoutsOfComponentAndSubComponents(this, 0);
}
public void add(JComponent component) {
layoutPanel.add(component);
}
}
}
The layoutPanel in your Fieldset class seems to stack the components on top of each other because it's default layout tells it to.
Just to get started, try setting a simple BoxLayout to it in the constructor of Fieldset:
this.layoutPanel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS));
Your button will be visible. So, the full constructor should look like this:
public Fieldset(String titleFieldset, JPanel panel, Color colorBorder) {
super();
this.border = new TitledBorder(new LineBorder(colorBorder == null ? Color.BLACK : colorBorder), titleFieldset);
this.setBorder(border);
this.layoutPanel = panel;
this.layoutPanel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS));
super.add(layoutPanel);
}