Java, Mac et parfois plus …

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.util.ArrayList;

import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;

/**
 * This is a swing class that handle Forms by managing lines.
 * In one line you can put a label (left), a component (auto resize - middle) and an other component (rigth)
 * @author Gabriel Dromard
 */
public class JForm extends JPanel {
    public static final long serialVersionUID = 364635478;
    private ArrayList leftComponents = new ArrayList();
    private ArrayList rightComponents = new ArrayList();
    private JPanel lastLine = null;
    private int hgap, vgap;

    private int rightWidth;
    private int leftWidth;

    /**
    * Initialization of the component
    * @param hgap the horizontal gap of the layout.
    * @param vgap the vertical gap of the layout.
    */
    public JForm(int hgap, int vgap) {
        super();
        this.hgap = hgap;
        this.vgap = vgap;
        this.setLayout(new BorderLayout(hgap, vgap));
        lastLine = this;
    }

    /**
    * Centralize creation of panels
    * @return A new instance of panel (with border layout and opaque false)
    */
    public JPanel buildPanel() {
        JPanel panel = new JPanel(new BorderLayout(hgap, vgap));
        panel.setOpaque(this.isOpaque());
        panel.setBackground(this.getBackground());
        return panel;
    }

    /**
    * Add a line to the form
    * @param label  The label (WEST)
    * @param middle A component (middle)
    * @param right  A component (EAST)
    */
    public void addLine(JLabel label, JComponent middle, JComponent right) {
        JPanel line = buildPanel();
        if(label != null) {
            leftWidth = addComponent(leftComponents, label, leftWidth);
            line.add(label, BorderLayout.WEST);
        }
        if(right != null) {
            rightWidth = addComponent(rightComponents, right, rightWidth);
            line.add(right, BorderLayout.EAST);
        }
        if(middle != null) {
            line.add(middle, BorderLayout.CENTER);
        }
        lastLine.add(line, BorderLayout.NORTH);
        JPanel nextLine = buildPanel();
        lastLine.add(nextLine, BorderLayout.CENTER);
        lastLine = nextLine;
    }

    /**
     * This methods is used to set width of left or rigth component. All the component on left must have the same width !
     * And it is the same for rigth ones.
     *
     * @param components The ArrayList of components.
     * @param component The component to add into the ArrayList.
     * @param maxSize The current max size of the components.
     * @return The new max size of the components
     */
    private int addComponent(ArrayList components, JComponent component, int maxSize) {
        int size = (int)component.getPreferredSize().getWidth();

        System.out.println("size="+size);
        System.out.println("maxSize="+maxSize);
        if (size > maxSize) {
            maxSize = size;
            adaptWidth(components, maxSize);
        } else {
            component.setPreferredSize(new Dimension(maxSize, (int)component.getPreferredSize().getHeight()));
        }

        components.add(component);

        return maxSize;
    }

    /**
     * This methods is used to adapt the prefered size of components of an array.
     *
     * @param components The components.
     * @param size The new prefered size.
     */
    private void adaptWidth(ArrayList components, int size) {
        JComponent cmp;
        // Set preferred size for left components
        for (int i=0; i<components.size(); i++) {
            cmp = ((JComponent)components.get(i));
            cmp.setPreferredSize(new Dimension(size, (int)cmp.getPreferredSize().getHeight()));
        }
    }

    /**
     * This is a way of testing this class.
     *
     * @param args Not used.
     */
    public static void main(String[] args) {
        JForm form = new JForm(5, 5);
        form.setBackground(Color.WHITE);
        form.setOpaque(true);

        for (int i = 0; i < 10; ++i) {
            if (i == 1) {
                form.addLine(new JLabel("JLabel n°" + i), new JTextField(), null);
            } else if (i == 2) {
                form.addLine(null, new JTextField(), new JButton("JButton n°" + i));
            } else if (i == 3) {
                form.addLine(null, new JTextField(), null);
            } else if (i == 4) {
                form.addLine(new JLabel("JLabel n°" + i), null, null);
            } else if (i == 5) {
                form.addLine(null, null, new JButton("JButton n°" + i));
            } else {
                form.addLine(new JLabel("JLabel n°" + i), new JTextField(), new JButton("JButton n°" + i));
            }
        }
        SwingHelper.openInFrame(form);
    }
}

Java