Unusual gaps while using JSeperator - Java

Question

I have been working on a Swing GUI and getting some unusual and unwanted gaps after adding JSeperator, Any idea how to remove them? Or any other option to how to achieve this nicely!

Visual Description

Gaps are apparent before JLabel "Speed" and after JSlider.

Related Code

control.setLayout(new BoxLayout(control, BoxLayout.X_AXIS));

...another code omitted...

control.add(orientation); //JLabel
control.add(norm); //JRadioButton
control.add(back); //JRadioButton
control.add(new JSeparator(SwingConstants.VERTICAL));
control.add(speedLabel); //JLabel
control.add(speed); //JSlider
control.add(new JSeparator(SwingConstants.VERTICAL));
control.add(turnOutLabel); //JLabel
control.add(right); //JRadioButton
control.add(straight); //JRadioButton
control.add(left); //JRadioButton

---

What I want is to Have have everything centred and separated by JSeperator,

Visual Description

Thank you.

Answer 1

Just replace new JSeparator(...) with the following lines (you can put them in a method if you want):

JSeparator separator = new JSeparator(JSeparator.VERTICAL);
Dimension size = new Dimension(
    separator.getPreferredSize().width,
    separator.getMaximumSize().height);
separator.setMaximumSize(size);

As @kleopatra explained, JSeparator has unbounded maximum size (in both directions), so the trick here is to limit the max width to the preferred width, but still keep the max height unchanged (because the preferred height is 0).