Swing not displaying the correct font set

Question

I have a JList inside of a JScrollPane and have set the font to Tahoma, plain, 20 and for some reason its still displaying as very small text and I am not to sure why this is?

Just so that this isn't a massive piece of code I have slimmed it down as much as I can the frame that this is stored in uses a GridBagLayout

ArrayUtil.ArrayToListModel converts any List<T>; to ListMode<T>;

JFrame frame = new JFrame();
frame.setBounds(100, 100, 450, 300);
frame.setDefaultCloseOperation(WindowConstants.HIDE_ON_CLOSE);
GridBagLayout gridBagLayout = new GridBagLayout();
gridBagLayout.columnWidths = new int[]{0};
gridBagLayout.rowHeights = new int[]{0};
gridBagLayout.columnWeights = new double[]{1.0};
gridBagLayout.rowWeights = new double[]{1.0};
frame.getContentPane().setLayout(gridBagLayout);

JScrollPane showlistScrollPane = new JScrollPane();
GridBagConstraints gbc_showlistScrollPane = new GridBagConstraints();
gbc_showlistScrollPane.insets = new Insets(0, 0, 0, 5);
gbc_showlistScrollPane.fill = GridBagConstraints.BOTH;
gbc_showlistScrollPane.gridx = 0;
gbc_showlistScrollPane.gridy = 0;
frame.getContentPane().add(showlistScrollPane, gbc_showlistScrollPane);

ArrayList<String> randomData = new ArrayList<String>();
randomData.add("Random drhgiudrhgiudhri");
randomData.add("Data dsirhgodhroih");
ListModel<String> pagesList = ArrayUtil.ArrayToListModel(randomData);

showlist = new JList<String>(pagesList);
showlist.setFont(new Font("Tahoma", Font.PLAIN, 20));
showlistScrollPane.setViewportView(showlist);

No matter how big or small I make the font for showlist it never changes from its default.

Answer 1

The means by which content is displayed within a JList is not defined by the JList but is defined by the ListCellRenderer assigned to the JList, so

showlist.setFont(new Font("Tahoma", Font.PLAIN, 20));

Will have no effect on the content displayed within the JList

Take a look at Writing a Custom Cell Renderer for more details

As an example...

import java.awt.Component;
import java.awt.EventQueue;
import java.awt.Font;
import javax.swing.DefaultListCellRenderer;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JScrollPane;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Test1 {

    public static void main(String[] args) {
        new Test1();
    }

    public Test1() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JList list = new JList(new String[]{"Happy list", "of happy things", "bunnies", "unicorns", "sharks"});
                list.setCellRenderer(new BigFontListCellRenderer());

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new JScrollPane(list));
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class BigFontListCellRenderer extends DefaultListCellRenderer {

        @Override
        public Component getListCellRendererComponent(JList<?> list, Object value, int index, boolean isSelected, boolean cellHasFocus) {
            super.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus);
            setFont(new Font("Tahoma", Font.PLAIN, 20));
            return this;
        }

    }

}