Swing - Change menu bar and menu items font size in runtime

Question

as title says, I need to change the font size of the menu bar and every item on it (and also the items of the ite,s) using SWING.

I have the following code which works but not on runtime, I need it to be when clicking on a menu item

Font f = new Font("sans-serif", Font.PLAIN, 12);
UIManager.put("Menu.font", f);
UIManager.put("MenuItem.font", f);

And the code I have for my menu is

private class foo{
        private JMenu mnArchivo;
        private JMenuBar menuBar;
        menuBar = new JMenuBar();
        frmAdministracinHospital.setJMenuBar(menuBar);

    JRadioButtonMenuItem rdbtnmntmGrande = new JRadioButtonMenuItem("Grande");
            rdbtnmntmGrande.addActionListener(new MiGrandeActionListener());
            rdbtnmntmGrande.setIcon(new ImageIcon(PrincipalWindow.class.getResource("/presentacion/fontbig.png")));
            buttonGroup.add(rdbtnmntmGrande);
            mnTamanoFuente.add(rdbtnmntmGrande);

    private class MiGrandeActionListener implements ActionListener {
            public void actionPerformed(ActionEvent e) {

                Font f = new Font(menuBar.getFont().getFontName(), menuBar.getFont().getStyle(), 12);
                UIManager.put("Menu.font", f);
            }
        }

I haven't found any similar question which does it on run time, how could I achieve this?

EDIT. CODE ADD WITH NO WORKING THE FONT SIZE CHANGE MORE THAN ONCE.

package presentacion;

import java.awt.EventQueue;
import java.awt.Font;
import java.awt.SystemColor;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.ButtonGroup;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JPanel;
import javax.swing.JRadioButtonMenuItem;
import javax.swing.JTabbedPane;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

import dominio.Appointment;
import dominio.Patient;
import dominio.Specialist;


public class pepe {

    private JFrame a;
    private JTabbedPane tabbedPane;
    private JMenuBar menuBar;
    private final ButtonGroup buttonGroup = new ButtonGroup();


    public pepe() {
        initialize();
        a.setVisible(true);
    }

    public static void main(String[] args) {

        try {
            // Set System L&F
        UIManager.setLookAndFeel(
            UIManager.getSystemLookAndFeelClassName());
    } 
    catch (UnsupportedLookAndFeelException e) {
       // handle exception
    }
    catch (ClassNotFoundException e) {
       // handle exception
    }
    catch (InstantiationException e) {
       // handle exception
    }
    catch (IllegalAccessException e) {
       // handle exception
    }

        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    pepe window = new pepe();
                    window.a.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    private void initialize() {
        a = new JFrame();
        a.setTitle("Administraci\u00F3n Hospital");
        a.setBounds(100, 100, 1195, 710);
        a.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        tabbedPane = new JTabbedPane(JTabbedPane.TOP);
        tabbedPane.setBackground(SystemColor.info);

        menuBar = new JMenuBar();
        a.setJMenuBar(menuBar);

        JMenu mnVer = new JMenu("Ver");
        menuBar.add(mnVer);

        JMenu mnTamanoFuente = new JMenu("Tama\u00F1o fuente");
        mnVer.add(mnTamanoFuente);

        JRadioButtonMenuItem rdbtnmntmPequeo = new JRadioButtonMenuItem("Peque\u00F1o");
        rdbtnmntmPequeo.addActionListener(new MiPequenaActionListener());
        buttonGroup.add(rdbtnmntmPequeo);
        mnTamanoFuente.add(rdbtnmntmPequeo);

        JRadioButtonMenuItem rdbtnmntmGrande = new JRadioButtonMenuItem("Grande");
        rdbtnmntmGrande.addActionListener(new MiGrandeActionListener());
        buttonGroup.add(rdbtnmntmGrande);
        mnTamanoFuente.add(rdbtnmntmGrande);

    }

    private class MiPequenaActionListener implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            Font f = new Font(a.getFont().getFontName(), a.getFont().getStyle(), 10);
            UIManager.put("Label.font", f);
            UIManager.put("Menu.font", f);
            UIManager.put("MenuItem.font", f);
            SwingUtilities.updateComponentTreeUI(a);

        }
    }

    private class MiGrandeActionListener implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            Font f = new Font(a.getFont().getFontName(), a.getFont().getStyle(), 13);
            UIManager.put("Label.font", f);
            UIManager.put("Menu.font", f);
            UIManager.put("MenuItem.font", f);
            SwingUtilities.updateComponentTreeUI(a);
        }
    }

}

With this it lets me change the font size just once, to big for example (grande) if then I click on small or normal it wont do anything.

Thank you.

Answer 1

I have the following code which works but not on runtime,

Font f = new Font(menuBar.getFont().getFontName(), menuBar.getFont().getStyle(), 12);
UIManager.put("Menu.font", f);

Basically you need to do a LAF change, so the above should be:

Font f = new FontUIResource(menuBar.getFont().getFontName(), menuBar.getFont().getStyle(), 12);
UIManager.put("Menu.font", f);
SwingUtilities.updateComponentTreeUI(frame);

You need to make sure the Font is a FontUIResource so the LAF can change the property.

Read the section from the Swing tutorial on Changing the LAF After Startup for more information and examples.