Java/Swing Box Layout with Separator

Question

Here is the code:

Box twoPanelBox= new Box(BoxLayout.Y_AXIS);
twoPanelBox.add(panelA); // red
twoPanelBox.add(new JSeparator(SwingConstants.HORIZONTAL) );
twoPanelBox.add(panelB); // black

And here is what i get:

The red and the black panel are displayed as expected, where the seperater ( green box around) has something like a margin between.

How can a avoid this marging, and eliminate this space (grey area)? Thank you

Ametropia

What L&F are you using? Try to put setContentMargin(new Insets(0,0,0,0)) – Townie

well this is the correct output, (but for other answerers to) for better help sooner post an SSCCE, short, runnable, compilable, just about JFrame with two JPanels and one JSeparator – Guelph

@nachokk: I'm using W7 standard [UIManager.setLookAndFeel( UIManager.getSystemLookAndFeelClassName())] – Ametropia

Answer 1

A little unexpectedly, BoxLayout will stretch the separator. However, this dirty hack will help:

JSeparator separator = new JSeparator(SwingConstants.HORIZONTAL);
separator.setMaximumSize( new Dimension(Integer.MAX_VALUE, 1) );
mergeBox.add(separator);

Ametropia

not dirty hack, BoxLayout accepting Min/Max and PreferredSize, JSeparator returns own PreferredSize, but there are another two ways – Guelph