CenteredLabelFrame.java

package com.weblogism;

import com.github.weisj.darklaf.LafManager;
import com.github.weisj.darklaf.theme.DarculaTheme;

import javax.swing.*;
import javax.swing.table.*;
import java.awt.*;

public class CenteredLabelFrame extends JFrame {

    static class DarkTableModel extends AbstractTableModel {

        int rows;
        int cols;
      
        public DarkTableModel(int rows, int cols) {
            this.rows = rows;
            this.cols = cols;
        }

        @Override
        public int getRowCount() {
            return rows;
        }

        @Override
        public int getColumnCount() {
            return cols;
        }

        @Override
        public Object getValueAt(int rowIndex, int columnIndex) {
            return "(" + rowIndex + ", " + columnIndex + ")";
        }
    }

    static class CenteredCellRenderer implements TableCellRenderer {
        private TableCellRenderer renderer;
      
        public CenteredCellRenderer(TableCellRenderer renderer) {
            this.renderer = renderer;
        }

        @Override
        public Component getTableCellRendererComponent(JTable table,
                                                       Object value,
                                                       boolean isSelected,
                                                       boolean hasFocus,
                                                       int row,
                                                       int column) {
            Component comp = renderer.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, column);
            if (comp instanceof JLabel) {
                JLabel label = (JLabel)comp;
                label.setHorizontalAlignment(JLabel.CENTER);
            }

            return comp;
        }
    }

    public CenteredLabelFrame() {
        setTitle("Lorem Ipsum");
        setSize(new Dimension(800, 400));
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      
        try {
            JPanel mainPanel = new JPanel();
            JTable aTable = new JTable();
            aTable.setModel(new DarkTableModel(10,10));
            for (int i = 0; i < aTable.getColumnCount(); i++) {
                TableColumn col = aTable.getColumn(aTable.getColumnName(i));
                col.setCellRenderer(new CenteredCellRenderer(aTable.getDefaultRenderer(Object.class)));
            }

            mainPanel.setLayout(new BorderLayout());
            mainPanel.add(new JScrollPane(aTable), BorderLayout.CENTER);
            getContentPane().setLayout(new BorderLayout());
            getContentPane().add(mainPanel, BorderLayout.CENTER);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }


    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
          // When commenting out the following line, all good.
            LafManager.install(new DarculaTheme());
            final CenteredLabelFrame frame = new CenteredLabelFrame();
            frame.setVisible(true);
        });
    }
}