I need some help with JPanel

[bantes]

hello. I have a JFrame, I use a container for this. Now, i want to add two JPanels to the container and then add the container to the JFrame. My problem is that I cannot set the "size" of the JPanels. I want the first Jpanel to take the 1/3 of the screen vertical, and the other JPanel to take the rest of the Jframe. How can I do that? panel.setSize and setPreferedSize does not work .
Do you have any suggestions?, because i really need it.
thank you

[PhHein]

Which LayoutManager do you use?

[bantes]

when i try to use the setsize and setpreferedsize i use borderlayout manager. I think that GridLayout is more flexible, but when i try to use it i get an exception error. I think that I am looking for a nice tutorial or a good code example on GridLayout. Here is my GridLayout code, which does not do the work and throws exception.

static JPanel p = new JPanel( ) ;
GridBagConstraints c = new GridBagConstraints();
c.gridx = 0;
c.gridy = 0;
c.gridwidth = 10;
c.gridheight = 10;
c.weightx = 30;
c.weighty = 30;
c.fill = GridBagConstraints.NONE;

p.setLayout(new GridBagLayout());
contentPane.add(p,c );

[bantes]

Here is the Exception
Exception in thread "main" java.lang.IllegalArgumentException: cannot add to layout: constraint must be a string (or null)

thanks for your interest mr. phHein

[PhHein]

Lesson: Laying Out Components Within a Container (The Java™ Tutorials > Creating a GUI With JFC/Swing)

[zweibieren]

In your code, the line "contentPane.add(p,c);" will cause the exception.
The second argument to add() must be a string name.
The layout manager will use this name to choose where to put the object in its layout.
GridBagLayout does not use this name. For GridBagLayout, the call is:

         gridbag.setConstraints(button, c);
         add(button);

You might consider using JSplitPane: How to Use Split Panes. Then there's no need for a layout manager.

[camickr]

Use a vertical BoxLayout and set the preferred size of each component.

[bantes]

JSplitPane is what I need. thank you guys.