How to create invisible space between 2 boxes

Question

I am trying to create a vertical space between 2 horizontal boxes in
a JPanel.
Following is the code sample i am using:
this.add(horizontalbox1,BorderLayout.NORTH);
this.add(Box.createVerticalStrut(3));
this.add(horizontalbox2,BorderLayout.CENTER);
this.add(Box.createVerticalStrut(3));
this.add(horizontalbox3,BorderLayout.SOUTH);
This doesn't work.
I tried using setBorder()to create empty Border method but that doesn't work too.

Answer 1

Looks like you're mixing layouts of the 'this' JPanel. You should set it to be a BoxLayout instead of a BorderLayout if that's what it currently is. If the 'this' JPanel is a BorderLayout you can only add things to the NORTH, SOUTH, EAST, or WEST. Where are your struts being added? Try the following instead.
setLayout(new BoxLayout(contentPane, BoxLayout.Y_AXIS));
add(horizontalbox1);
add(Box.createVerticalStrut(3));
add(horizontalbox2);
add(Box.createVerticalStrut(3));
add(horizontalbox3);