如何在JFrame上为所有JPanel设置setVisible

Question

How can I setVisible for all JPanel on JFrame? I know that I can use JFrame.JPanel.setVisible for each panel, but I'd like do it ones for all.

It's very usefull because I don't know witch panel are visible. So I want hide all panel after action and show 1 or 2 panels.

Answer 1

Simple solution :

store all your panels as instances or in a list

Generic solution :

iterate the widget tree

private void setAllChildPanelsVisible(Container parent) {
    Component[] components = parent.getComponents();

    if (components.length > 0) {
        for (Component component : components) {
            if (component instanceof JPanel) {
                ((JPanel) component).setVisible(true);
            }
            if (component instanceof Container) {
                setAllChildPanelsVisible((Container) component);
            }
        }
    }
}

How to use it:

@Test
public void testSetAllChildPanelsVisible() {
    JFrame frame = new JFrame();

    JPanel panel1 = new JPanel();
    frame.getContentPane().add(panel1);

    JPanel panel2 = new JPanel();
    panel1.add(panel2);

    panel1.setVisible(false);
    panel2.setVisible(false);

    assertFalse(panel1.isVisible());
    assertFalse(panel2.isVisible());

    setAllChildPanelsVisible(frame.getContentPane());

    assertTrue(panel1.isVisible());
    assertTrue(panel2.isVisible());
}

Answer 2

Here's a generic method which does this. It recurively iterates through all the components in a container hierarchy, finds the ones that match a particular component class, and sets their visible property:

static void setComponentVisibility(Container container,
        Class<? extends Component> componentClass, boolean visible) {
    for (Component c : container.getComponents()) {
        if (componentClass.isAssignableFrom(c.getClass())) {
            c.setVisible(visible);
        } else if (c instanceof Container) {
            setComponentVisibility((Container)c, componentClass, visible);
        }
    }
}

Use it something like this:

setComponentVisibility(frame, JPanel.class, false);