Use ComponentListener to resize font when the size of a JPanel / JFrame is changed

After a container is maximized or stretched to a very large size, the initial font may be too small to look nice in the big container. One way to resize the font according to the size of the container is through a ComponentListener. Below is a sample code.

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.plaf.FontUIResource;

public class PanelFontResize extends JFrame {

    private JPanel thePanel;
    private JLabel theLabel;
    private JTextField theText;
    private JTable theTable;

    public PanelFontResize() {

        theLabel = new JLabel("The Topic: ");
        theText = new JTextField("Does the Sun rise the same time each day?");
        JPanel northPane = new JPanel(new GridBagLayout());
        northPane.add(theLabel, new GridBagConstraints(0,0,1,1,1.0,1.0,GridBagConstraints.EAST, GridBagConstraints.NONE, new Insets(0,0,0,5),0,0));
        northPane.add(theText, new GridBagConstraints(1,0,2,1,2.0,1.0,GridBagConstraints.WEST, GridBagConstraints.NONE, new Insets(0,0,0,0),0,0));
     
        String[] colnames = {"Season", "Sun Rise"};
        String[][] data = {{"Spring", "6:00"},
                    {"Summer", "5:30"},
                    {"Autum", "6:30"},
                    {"Winter", "7:00"}};
        theTable = new JTable(data, colnames);
        JScrollPane sp = new JScrollPane(theTable);
     
        thePanel = new JPanel(new BorderLayout());
        thePanel.add(northPane, BorderLayout.NORTH);
        thePanel.add(sp, BorderLayout.CENTER);
        thePanel.addComponentListener(new PanelListener());
     
        setContentPane(thePanel);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(300, 200);
        validate();
        setVisible(true);
    }
 
 
    private class PanelListener extends ComponentAdapter {

        @Override
        public void componentResized(ComponentEvent e) {
            Dimension psize = thePanel.getSize();
            if (psize.width <= 761 && psize.height <= 551) {
                setFonts(11);
            } else if (psize.width <= 984 && psize.height <= 617
                    && psize.width > 761 && psize.height > 551) {
                setFonts(13);
            } else if (psize.width <= 1046 && psize.height <= 762
                     && psize.width > 984 && psize.height > 617) {
                setFonts(15);
            } else if (psize.width <= 1245 && psize.height <= 867
                    && psize.width > 1046 && psize.height > 762) {
                setFonts(18);
            } else if (psize.width > 1245 && psize.height > 867){
                setFonts(20);
            }
        }
    }
 
    public void setFonts(int fontSize) {

        Font plainFont = new Font("Dialog", Font.PLAIN, fontSize);
        Font boldFont = new Font("Dialog", Font.BOLD, fontSize + 2);

        UIManager.put("Text.font", new FontUIResource(plainFont));
        UIManager.put("TextField.font", new FontUIResource(plainFont));
        UIManager.put("Table.font", new FontUIResource(plainFont));
        UIManager.put("Label.font", new FontUIResource(boldFont));
        UIManager.put("TableHeader.font", new FontUIResource(boldFont));
        UIManager.put("Panel.font", new FontUIResource(plainFont));
        UIManager.put("ScrollPane.font", new FontUIResource(plainFont));
     
        setTableSize(fontSize);
        SwingUtilities.updateComponentTreeUI(thePanel);
    }
 
    private void setTableSize(int fontSize){
            Font f = getFont().deriveFont((float)fontSize);
            theTable.setRowHeight(new Float(f.getSize2D() * 1.5).intValue());
    }
 
    public static void main(String[] args){
        new PanelFontResize();
    }
}

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