First Attempt

You might think that you could use a BorderLayout, and simply add the three buttons all to the South. So your code might look like:

package swingExamples;

import java.awt.BorderLayout;
import java.awt.Container;

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

class NestedLayouts1Panel extends JPanel
{
  public NestedLayouts1Panel()
  {
    setLayout(new BorderLayout());
    add(m_yellow, BorderLayout.SOUTH);
    add(m_blue, BorderLayout.SOUTH);
    add(m_red, BorderLayout.SOUTH);
  }

  ////////////// Data //////////////////
  private JButton m_yellow = new JButton("Yellow");
  private JButton m_blue = new JButton("Blue");
  private JButton m_red = new JButton("Red");
}

class NestedLayouts1Frame extends JFrame
{
  public NestedLayouts1Frame()
  {
    setTitle("NestedLayouts");
    setSize(300, 200);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    Container contentPane = getContentPane();
    contentPane.add( new NestedLayouts1Panel() );
  }
}

public class NestedLayouts1
{
  public static void main(String[] args)
  {
    NestedLayouts1Frame frame = new NestedLayouts1Frame();
    frame.setVisible(true);
  }
}

Notice that only the last component to be added to the south is the one that actually resides there.