import java.awt.Color;
import java.awt.Component;

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.table.AbstractTableModel;
import javax.swing.table.DefaultTableCellRenderer;
import javax.swing.table.TableCellRenderer;
import javax.swing.table.TableModel;


public class App {

    public static class BGCellRenderer extends DefaultTableCellRenderer {
        private Color bgcolor;

        public BGCellRenderer(Color bgcolor) {
            this.bgcolor = bgcolor;
        }

        @Override
        public Component getTableCellRendererComponent(JTable table,
                Object obj, boolean isSelected, boolean hasFocus, int row,
                int col) {
            Component comp = super.getTableCellRendererComponent(table, obj,
                    isSelected, hasFocus, row, col);
            if (!isSelected) {
                if (obj instanceof EmptyCell) {
                    comp.setBackground(bgcolor);
                } else {
                    comp.setBackground(Color.WHITE);
                }
            }
            return comp;
        }
    }

    public static class Cell {  }

    public static class EmptyCell extends Cell {
    }

    public static class RealCell extends Cell {
    }

    public static class MyModel extends AbstractTableModel {
        private Cell[][] data;
        private int width;
        private int height;

        public MyModel(int width, int height) {
            this.width = width;
            this.height = height;
            data = new Cell[width][height];
            for (int i = 0; i < width; i++) {
                for (int j = 0; j < height; j++) {
                    if (i == j) {
                        data[i][j] = new EmptyCell();
                    } else {
                        data[i][j] = new RealCell();
                    }
                }
            }
        }

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

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

        @Override
        public Object getValueAt(int i, int j) {
            return data[i][j];
        }

    }

    public static void main(String[] args) {

        TableModel model = new MyModel(5, 10);
        final BGCellRenderer bgrenderer = new BGCellRenderer(Color.GREEN);
        JTable table = new JTable(model) {
            public TableCellRenderer getCellRenderer(int row, int column) {
                return bgrenderer;
            }
        };

        JFrame f = new JFrame("rejtvény");
        f.getContentPane().add(new JScrollPane(table));
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setSize(600, 400);
        f.setVisible(true);
    }
}