How to fix height on JPanel?

Question

Hello,
I have three subPanels, all sitting on a JFrame.
I want to fix the height of the top and bottom panels, but have the middle panel always be the max allowed space.
For example, top Panel is always 50 pixels tall, bottom panel is always 30 pixels tall. Depending on the size of the main panel, the middle panel will always be:
JFrameHeight-50-30=middlePanelHeight.
I don't want to use setMaximumSize or setPreferred size, because that will fix my width, and I don't want to fix the width. I want it to grow as wide as the JFrame itself. The only thing I want to fix is the HEIGHT of the top and bottom panels on the JFrame.
I am using BoxLayout (with Y_AXIS). Right now, I am using setMaximumSize - that will fix my height - but also fixes my width (because it takes dimension(width,height), which I don't want to do.
Can anyone help me?
If you need code, please request, and I will post.
Apologies if this question already answered, I couldn't find it answered anywhere. :)
Nina.

Answer 1

Hello,
Yes, you are all correct, BorderLayout should work.
You guys really did get me closer to the solution.
Now, I think it's the topPane's Layout Manager
that keeps it from working right.
What I want to do, is the top panel (outlined in
the black box) to always stretch so that the words
are always fully justified at the left and right
edge. That means, the word "Age: 3",
"NinaCute", "Pet Name", "Nina Screen" are all
flushed to the sides.
Posted below is code. You'll see that if you
make the window wider, the words don't remain
flushed with the edges.
import javax.swing.*;
import javax.swing.border.LineBorder;
import javax.swing.text.*;
import javax.swing.event.*;
import java.awt.*;              //for layout managers
import java.awt.event.*;        //for action and window events
import java.util.*;
public class NinaDialog extends JDialog
          public NinaDialog(JFrame frame)
                    super(frame, true);
          public void buildWindow()
                    Container contentPane=this.getContentPane();
                    BorderLayout bord=new BorderLayout();
                    contentPane.setLayout(bord);
                    this.setSize(600, 500);
                    JPanel topPane=createHeaderPane();
                    contentPane.add(topPane, bord.NORTH);
                    // create the reservation tab panel and add it
                    JPanel midPane=createMiddlePane();
                    contentPane.add(midPane, bord.CENTER);
                    JPanel btnPane=createButtonPane();
                    contentPane.add(btnPane, bord.SOUTH);
                    this.addWindowListener(new WindowAdapter()
                              public void windowClosing(WindowEvent e)
                              } // end windowCloseing
                    }); // end windowListener
          } // end buildWindow
          public JPanel createHeaderPane()
                    JPanel topPane=new JPanel();
                    topPane.setBorder(new LineBorder(Color.black));
                    GridBagLayout gb=new GridBagLayout();
                    GridBagConstraints gc=new GridBagConstraints();
                    topPane.setLayout(gb);
                    JLabel label=new JLabel(htmlIt("<b>Nina Screen</b> | "+
                    "<b>Folder:</b> Images"+
                    " | <b>Current Status:</b> FULL"));
                    gc.gridx=0; gc.gridy=0; gc.gridwidth=3;
                    gc.anchor=gc.NORTHWEST; gc.insets=new Insets(0,2,4,50);
                    gb.setConstraints(label,gc);
                    topPane.add(label);
                    label=new JLabel(htmlIt("<b>User Id:</b> NinaCute"));
                    gc.gridx+=3; gc.gridwidth=1; gc.anchor=gc.NORTHEAST;
                    gc.insets=new Insets(0,0,4,2);
                    gb.setConstraints(label,gc);
                    topPane.add(label);
                    gc.gridy++; gc.insets=new Insets(0,2,2,20);
                    label=new JLabel(htmlIt("<b>Pet Name:</b> Joe"));
                    gc.gridx=0; gc.anchor=gc.NORTHWEST;
                    gb.setConstraints(label,gc);
                    topPane.add(label);
                    label=new JLabel(htmlIt("<b>Type:</b> Bunny"));
                    gc.gridx++; gc.insets=new Insets(0,0,2,20);
                    gb.setConstraints(label,gc);
                    topPane.add(label);
                    label=new JLabel(htmlIt("<b>Color:</b> Black/White"));
                    gc.gridx++; gc.insets=new Insets(0,0,2,20);
                    gb.setConstraints(label,gc);
                    topPane.add(label);
                    gc.insets=new Insets(0,0,2,2);
                    label=new JLabel(htmlIt("<b>Age:</b> 3"));
                    gc.gridx++; gc.anchor=gc.NORTHEAST;
                    gb.setConstraints(label,gc);
                    topPane.add(label);
                    return topPane;
          } // end createHeaderPane
          public JPanel createMiddlePane()
                    // add in closeButton
                    JPanel pane=new JPanel();
                    //pane.setBorder(new LineBorder(Color.black));
                    GridBagLayout gb=new GridBagLayout();
                    GridBagConstraints gc=new GridBagConstraints();
                    pane.setLayout(gb);
                    JLabel label=new JLabel("this window should stretch "+
                    "and resize horizontally and vertically.");
                    gc.gridx=0; gc.gridy=0; gc.anchor=gc.NORTH;
                    gb.setConstraints(label,gc);
                    pane.add(label);
                    return pane;
          } // end createMiddlePane
          public JPanel createButtonPane()
                    // add in closeButton
                    JPanel btnPane=new JPanel();
                    btnPane.setAlignmentX(JComponent.LEFT_ALIGNMENT);
                    //btnPane.setBorder(new LineBorder(Color.black));
                    GridBagLayout gb=new GridBagLayout();
                    GridBagConstraints gc=new GridBagConstraints();
                    btnPane.setLayout(gb);
                    gc.gridx=0; gc.gridy=0; gc.anchor=gc.EAST; gc.ipadx=8;
                    gc.weightx=1.0; gc.insets=new Insets(0,0,0,4);
                    JButton closeButton=new JButton("Close Window");
                    closeButton.addActionListener(new CancelListener());
                    gb.setConstraints(closeButton, gc);
                    btnPane.add(closeButton);
                    return btnPane;
          } // end createButtonPane
          private String htmlIt(String text)
                    if(text==null) return "";
                    String ret="<HTML>"+
                    "<font face=\"arial, helvetica\" size=\"2\">"+
                    text+
                    "</font>"+
                    "</HTML>";
                    return ret;
          } // end niceFormatLabel
          class CancelListener implements ActionListener
                    public void actionPerformed(ActionEvent e)
                              closeWindow();
                    } // end actionPerformed
          } // end CancelListener
          public void closeWindow()
                    WindowEvent we = new WindowEvent(this, WindowEvent.WINDOW_CLOSING);
                    this.processWindowEvent(we);
          } // end closeWindow
          public void showDialog()
                    this.show();
                    return;
          public void show()
                    this.setTitle("Fulillment | Reservation | Cruise");
                    super.show(); // makes it block until it gets some closeevent
          public static void main(String[] args)
                    JFrame frame=new JFrame();
                    NinaDialog dig=new NinaDialog(frame);
                    // build the UI
                    dig.buildWindow();
                    // show the Dialog and don't close until closewindow clicked
                    dig.showDialog();
          } // end main
} // end class