PositionLayout in Java

import java.awt.Container;
import java.util.ArrayList;
import java.util.List;

import javax.swing.JButton;
import javax.swing.JFrame;

import org.tobiasbelch.java.javui.layout.AbsoluteConstraint;
import org.tobiasbelch.java.javui.layout.Constraint;
import org.tobiasbelch.java.javui.layout.PositionLayout;
import org.tobiasbelch.java.javui.layout.Property;
import org.tobiasbelch.java.javui.layout.RelativeConstraint;

public class PLTest {
    public static void addComponentsToPane(Container pane) {
        List<Constraint<?>> constraints = new ArrayList<Constraint<?>>();
        constraints.add(new AbsoluteConstraint (Property.Left, 10));
        constraints.add(new RelativeConstraint (Property.Right, 0.50f));
        constraints.add(new AbsoluteConstraint (Property.Top, 10));
        constraints.add(new AbsoluteConstraint (Property.Bottom, 10));

        pane.add(new JButton("Button"), constraints);

        constraints = new ArrayList<Constraint<?>>();
        constraints.add(new RelativeConstraint (Property.HCenter, .125f));
        constraints.add(new AbsoluteConstraint (Property.Top, 10));
        constraints.add(new RelativeConstraint (Property.Width, .25f));
        constraints.add(new RelativeConstraint (Property.Height, .25f));


        pane.add(new JButton("Button"), constraints);
    }

    private static void createAndShowGUI() {

        JFrame frame = new JFrame("Demo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        Container c = frame.getContentPane();
        c.setLayout(new PositionLayout());
        addComponentsToPane(c);
        frame.pack();
        frame.setVisible(true);

        System.out.println(c);
    }

    public static void main(String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}