GridBagLayout... Components always centered vertically?

[Shawn Rieger]

I have a panel, in it a few components. I've gotten the components inside the panel to line up just how I want them. But when I add the panel to the frame at location 0,0 (Should be Top Left) its still centered vertically on the frame. Why is this? I just want my components to start out in the top left hand corner of my frame and span out from there. How can I do this. My code is below...

import java.awt.*;
import javax.swing.*;
 
public class PaintTest extends JFrame {

public static void main(String[] args) {
PaintTest frame = new PaintTest();
frame.setSize(420, 380);
//frame.setResizable(false);
frame.setTitle("Paint Estimator");
frame.setVisible(true);
}

private JPanel pnlMid = new JPanel();
private JLabel lblWidth = new JLabel("Width",JLabel.RIGHT);
private JLabel lblHeight = new JLabel("Height",JLabel.RIGHT);
private JTextField txtWidth = new JTextField("0");
private JTextField txtHeight = new JTextField("0");
private JButton btnAdd = new JButton("Add");
private JButton btnInsert = new JButton("Insert");
private JButton btnModify = new JButton("Modify");
private JButton btnDelete = new JButton("Delete");

private Container con = getContentPane();
private GridBagConstraints gbc = new GridBagConstraints();

public PaintTest() {
con.setLayout(new GridBagLayout());
gbc.fill = GridBagConstraints.BOTH;
gbc.anchor = GridBagConstraints.NORTHWEST;
gbc.insets = new Insets(1,1,1,1);
/* row one */
addComp(lblWidth,0,1,1,1,1,0);
addComp(txtWidth,0,2,1,2,2,0);
addComp(btnAdd,0,4,1,1,.2,0);
/* row two */
addComp(lblHeight,1,1,1,1,1,0);
addComp(txtHeight,1,2,1,2,2,0);
addComp(btnInsert,1,4,1,1,.2,0);
/* row three */
addComp(btnModify,2,4,1,1,.2,0);
addComp(btnDelete,3,4,1,1,.2,0);
}
 
private void addComp(Component c, int row, int column, int numberOfRows, int numberOfColumns,
double weightx, double weighty) {
gbc.gridx = column;
gbc.gridy = row;
gbc.gridwidth = numberOfColumns;
gbc.gridheight = numberOfRows;
gbc.weightx = weightx;
gbc.weighty = weighty;
con.add(c, gbc);
}
}

[Craig Wood]

import java.awt.*;
import javax.swing.*;
 
public class PTest extends JFrame {
 
    public static void main(String[] args) {
        PTest frame = new PTest();
        frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
        frame.setSize(420, 380);
        //frame.setResizable(false);
        frame.setTitle("Paint Estimator");
        frame.setVisible(true);
    }
 
    private JPanel pnlMid = new JPanel();
    private JLabel lblWidth = new JLabel("Width",JLabel.RIGHT);
    private JLabel lblHeight = new JLabel("Height",JLabel.RIGHT);
    private JTextField txtWidth = new JTextField("0");
    private JTextField txtHeight = new JTextField("0");
    private JButton btnAdd = new JButton("Add");
    private JButton btnInsert = new JButton("Insert");
    private JButton btnModify = new JButton("Modify");
    private JButton btnDelete = new JButton("Delete");
 
    private Container con = getContentPane();
    private GridBagConstraints gbc = new GridBagConstraints();
 
    public PTest() {
        con.setLayout(new GridBagLayout());
        gbc.fill = GridBagConstraints.HORIZONTAL;  // requires weightx > 0
        gbc.anchor = GridBagConstraints.NORTH;     // requires weighty > 0
        gbc.insets = new Insets(1,1,1,1);
        // weigthy = 0 -> all components will be clumped together
        // in the vertical dimension
        // row one         r  c  h  w  x    y
        addComp(lblWidth,  0, 1, 1, 1, 1,   0);
        addComp(txtWidth,  0, 2, 1, 2, 2,   0);
        addComp(btnAdd,    0, 4, 1, 1, 0.2, 0);
        /* row two */
        addComp(lblHeight, 1, 1, 1, 1, 1,   0);
        addComp(txtHeight, 1, 2, 1, 2, 2,   0);
        addComp(btnInsert, 1, 4, 1, 1, 0.2, 0);
        /* row three */
        addComp(btnModify, 2, 4, 1, 1, 0.2, 0);
        addComp(btnDelete, 3, 4, 1, 1, 0.2, 1.0);  // weighty > 0 -> push up/NORTH
        //             adding the zero ^ can make a difference
    }
 
    private void addComp(Component c, int row, int column,
                         int numberOfRows, int numberOfColumns,
                         double weightx, double weighty) {
        gbc.gridx      = column;
        gbc.gridy      = row;
        gbc.gridwidth  = numberOfColumns;
        gbc.gridheight = numberOfRows;
        gbc.weightx    = weightx;
        gbc.weighty    = weighty;
        con.add(c, gbc);
    }
}