为JToolbar创建复合Swing组件

Question

When using setRollover(true), buttons on Swing toolbars are flat without border and the border is drawn only when hovering/pushing the button. However, if the buttons are first added to a panel, and then the panel is added to the toolbar, this does not work. Is there some easy way how to achieve it?

I want the buttons to be in a JPanel to make them act as a single component (imagine a paging component with first/prev/next/last page buttons). I also want it to work regardless of L&F (as it would if the JPanel was not between the toolbar and the buttons).

EDIT:

Compare the buttons One & Two (added directly) with buttons Three & Four (added via a JPanel) in the following example:

import javax.swing.*;

public class ToolbarTest extends JFrame {
    ToolbarTest() {
        JToolBar toolbar = new JToolBar();
        toolbar.setRollover(true);

        JButton button = new JButton("One");
        button.setFocusable(false);
        toolbar.add(button);

        button = new JButton("Two");
        button.setFocusable(false);
        toolbar.add(button);

        JPanel panel = new JPanel();
        button = new JButton("Three");
        button.setFocusable(false);
        panel.add(button);

        button = new JButton("Four");
        button.setFocusable(false);
        panel.add(button);

        toolbar.add(panel);

        add(toolbar);
        pack();
    }

    public static void main(String[] args) throws Throwable {
        // optional: set look and feel (some lf might ignore the rollover property)
        for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
            if ("Nimbus".equals(info.getName())) {      // or "Windows", "Motif"
                javax.swing.UIManager.setLookAndFeel(info.getClassName());
                break;
            }
        }

        ToolbarTest frame = new ToolbarTest();
        frame.setVisible(true);
    }
}

Here are the screenshots:

The toolbar on Nimbus LF:

The same toolbar when mouse hovers over the second button (the mouse cursor is not shown):

The same toolbar on Windows LF:

I would like the Three and Four buttons to work the same way as the One and Two buttons.

Answer 1

1) I'd suggesting to set JMenuBar as container rather than JToolbar ,

disadvantages:

• isn't moveable and detachable, nor out of Container

• could by placed everywhere but only inside Container, like as another JComponent by using LayoutManager

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2) for JToolBar would be better to place there one JPanel nested another JComponents , as shows from your code example

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3) in your code example you define one JButton fouth times, in Java is required define as separate Objects

Answer 2

Using another JToolbar instead of JPanel works.

But: then I would probably (or maybe not?) have a problem, if I wanted to include the composite component into a dialog or something else than a toolbar. (This would be similar to having two types of buttons, one for toolbars and one for the rest)

this is the portion of the code from the question adding a panel changed to add a toolbar.

JToolBar component = new JToolBar();
component.setRollover(true);
component.setBorder(null);
component.setFloatable(false);

button = new JButton("Three");
button.setFocusable(false);
component.add(button);

button = new JButton("Four");
button.setFocusable(false);
component.add(button);

toolbar.add(component);