GridBagLayout - Vertically positioning components

Question

Trying to align a form next to my JTable with GridBagLayout and I am struggling to get my components to the top of the panel. I need the price label and fields just underneath the item label and field but I cannot get it to move from the bottom of the panel.

If I use anchor = GridConstraints.NORTHWEST, this moves the item label and field to the top, but then I lose the ability to anchor it with LINE_END. Unless there is a way to do both? Please see my image where I have attempted to demonstrate the area I want to place my form. Appreciate any help.

GridBagConstraints gbc = new GridBagConstraints();

// TEST COMPONENTS
JLabel lblItem = new JLabel("Item: ");
JLabel lblPrice = new JLabel("Price: ");
JLabel lblQuantity = new JLabel ("Quantity: ");

JTextField itemField = new JTextField(15);
JTextField pricePoundsField = new JTextField(3);
JTextField pricePenceField = new JTextField(2);
JTextField quantityField = new JTextField(3);

gbc.gridx = 0;
gbc.gridy = 0;
//gbc.weightx = 1.0;
//gbc.weighty = 1.0;
gbc.anchor = GridBagConstraints.LINE_START;
panelStockTable.add(jsp, gbc);

gbc.gridx = 1;
gbc.gridy = 0;
gbc.anchor = GridBagConstraints.LINE_END;
panelStockTable.add(lblItem, gbc);

gbc.gridx = 1;
gbc.gridy = 1;
panelStockTable.add(lblPrice, gbc);

gbc.anchor = GridBagConstraints.LINE_START;
gbc.gridx = 2;
gbc.gridy = 0;
panelStockTable.add(itemField, gbc);

gbc.gridx = 2;
gbc.gridy = 1;
panelStockTable.add(pricePoundsField, gbc);

Answer 1

The more complex a UI becomes, the more you want to focus on isolating the functionality and layouts to their own containers/classes.

This is where the concept of compounding layouts becomes very powerful. Rather then laying the fields out directly onto the same container as the table, use a separate container for them

Here, the right panel is standing in for the table and the blue panel is demonstrating the compounding container...

import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Test {

    public static void main(String[] args) {
        new Test();
    }

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        public TestPane() {
            setLayout(new GridBagLayout());
            GridBagConstraints gbc = new GridBagConstraints();

            JPanel stockTableProxy = new JPanel() {
                @Override
                public Dimension getPreferredSize() {
                    return new Dimension(200, 150);
                }
            };
            stockTableProxy.setBackground(Color.RED);

            gbc.gridx = 0;
            gbc.gridy = 0;
            gbc.weightx = 1.0;
            gbc.weighty = 1.0;
            gbc.fill = GridBagConstraints.BOTH;
            gbc.anchor = GridBagConstraints.LINE_START;
            add(stockTableProxy, gbc);


            JPanel fieldsPanel = new JPanel(new GridBagLayout());
            fieldsPanel.setBackground(Color.BLUE);

            // TEST COMPONENTS
            JLabel lblItem = new JLabel("Item: ");
            JLabel lblPrice = new JLabel("Price: ");
            JLabel lblQuantity = new JLabel("Quantity: ");

            JTextField itemField = new JTextField(15);
            JTextField pricePoundsField = new JTextField(3);
            JTextField pricePenceField = new JTextField(2);
            JTextField quantityField = new JTextField(3);

            gbc = new GridBagConstraints();
            gbc.gridx = 1;
            gbc.gridy = 0;
            gbc.anchor = GridBagConstraints.LINE_END;
            fieldsPanel.add(lblItem, gbc);

            gbc.gridx = 1;
            gbc.gridy = 1;
            fieldsPanel.add(lblPrice, gbc);

            gbc.anchor = GridBagConstraints.LINE_START;
            gbc.gridx = 2;
            gbc.gridy = 0;
            fieldsPanel.add(itemField, gbc);

            gbc.gridx = 2;
            gbc.gridy = 1;
            fieldsPanel.add(pricePoundsField, gbc);

            gbc.gridx = 0;
            gbc.gridy = 20;
            gbc.gridwidth = GridBagConstraints.REMAINDER;
            gbc.weighty = 1;
            fieldsPanel.add(new JLabel(), gbc);

            gbc = new GridBagConstraints();
            gbc.gridx = 1;
            gbc.gridy = 0;
            gbc.anchor = GridBagConstraints.LINE_END;
            gbc.fill = GridBagConstraints.VERTICAL;
            add(fieldsPanel, gbc);
        }

    }

}

But wait, there is more...

gbc.gridx = 0;
gbc.gridy = 20;
gbc.gridwidth = GridBagConstraints.REMAINDER;
gbc.weighty = 1;
fieldsPanel.add(new JLabel(), gbc);

This is a little trick you can use to force component to move to different edges of the container, here, I've used it to push all the fields to the top of the container.

All it does is add a transparent component (in this a JLabel) and provides all the left over space to it, neat