FlowLayout Vertical

package guj;

import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.EventQueue;

import javax.swing.Box;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JSplitPane;
import javax.swing.UIManager;

public class TesteBoxLayout extends JFrame {
    private JSplitPane splitPane;
    private JPanel pnlMenu;
    private JPanel pnlContents;
    private JButton btnFile;
    private JButton btnEdit;
    private JButton btnWindow;
    private JButton btnHelp;
    private Component verticalStrut;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        try {
            UIManager.setLookAndFeel("com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel");
        } catch (Throwable e) {
            e.printStackTrace();
        }
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    TesteBoxLayout frame = new TesteBoxLayout();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the frame.
     */
    public TesteBoxLayout() {
        setTitle("Exemplo BoxLayout");
        setBounds(100, 100, 450, 300);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        getContentPane().setLayout(new BorderLayout(0, 0));
        getContentPane().add(getSplitPane());

    }

    private JSplitPane getSplitPane() {
        if (splitPane == null) {
            splitPane = new JSplitPane();
            splitPane.setLeftComponent(getPnlMenu());
            splitPane.setRightComponent(getPnlContents());
        }
        return splitPane;
    }

    private JPanel getPnlMenu() {
        if (pnlMenu == null) {
            pnlMenu = new JPanel();
            pnlMenu.setLayout(new BoxLayout(pnlMenu, BoxLayout.Y_AXIS));
            pnlMenu.add(getBtnFile());
            pnlMenu.add(getBtnEdit());
            pnlMenu.add(getBtnWindow());
            pnlMenu.add(getVerticalStrut());
            pnlMenu.add(getBtnHelp());
        }
        return pnlMenu;
    }

    private JPanel getPnlContents() {
        if (pnlContents == null) {
            pnlContents = new JPanel();
        }
        return pnlContents;
    }

    private JButton getBtnFile() {
        if (btnFile == null) {
            btnFile = new JButton("File");
            btnFile.setAlignmentX(Component.RIGHT_ALIGNMENT);
        }
        return btnFile;
    }

    private JButton getBtnEdit() {
        if (btnEdit == null) {
            btnEdit = new JButton("Edit");
            btnEdit.setAlignmentX(Component.RIGHT_ALIGNMENT);
        }
        return btnEdit;
    }

    private JButton getBtnWindow() {
        if (btnWindow == null) {
            btnWindow = new JButton("Window");
            btnWindow.setAlignmentX(Component.RIGHT_ALIGNMENT);
        }
        return btnWindow;
    }

    private JButton getBtnHelp() {
        if (btnHelp == null) {
            btnHelp = new JButton("Help");
            btnHelp.setAlignmentX(Component.RIGHT_ALIGNMENT);
        }
        return btnHelp;
    }

    private Component getVerticalStrut() {
        if (verticalStrut == null) {
            verticalStrut = Box.createVerticalStrut(20);
        }
        return verticalStrut;
    }
}