Setting panel at center of screen by using layout

Question

I tried setting the position of child-panel at the center of parent-panel by using

parent_panel.setLayout(new BorderLayout());
parent_panel.add(child_panel, BorderLayout.CENTER);

But it's getting added at the middle of horizontal screen but vertically at top.

What do I need to do to add it at center of screen vertically and horizontally?

Answer 1

If I understand correctly, you want an interface something like this:

+-------- Parent panel --------+
|                              |
|                              |
|    +--- Child panel ----+    |
|    |                    |    |
|    |                    |    |
|    |                    |    |
|    |                    |    |
|    +--------------------+    |
|                              |
|                              |
+------------------------------+

...and you have no other components being added to the parent panel.

If this is the case, you have two choices that I know of (based on this question, which I apparently answered):

1. Use a GridBagLayout with an empty GridBagConstraints object, like this:

   parent_panel.setLayout(new GridBagLayout());
   parent_panel.add(child_panel, new GridBagConstraints());
   

2. Use a BoxLayout, like this:

   parent_panel.setLayout(new BoxLayout(parent_panel, BoxLayout.PAGE_AXIS));
   Box horizontalBox = Box.createHorizontalBox(); 
   horizontalBox.add(Box.createHorizontalGlue()); 
   horizontalBox.add(child_panel); 
   horizontalBox.add(Box.createHorizontalGlue()); 
   Box verticalBox = Box.createVerticalBox(); 
   verticalBox.add(Box.createVerticalGlue()); 
   verticalBox.add(horizontalBox); // one inside the other
   verticalBox.add(Box.createVerticalGlue());