Add color to JTable rows

Question

I Want change the color of my JTable rows.

When i set a row in JTable,The first row become RED color.And then when i want add new row the first row become yellow and the second row become red;

I do not use repaint() Becouse repaint all time work.I want just one time.When i Use repaint or tablemodel.setfile... the table constantly update

Answer 1

This can be done with a custom cell renderer .

A cell renderer is responsible for creating a Component which the cells actually display. (The cell renderer Component is not actually added to the JTable. The JTable just uses it to do painting.) DefaultTableCellRenderer creates JLabels so you can set their background and foreground colors freely. You don't need to do painting.

You can pretty much display the cells however you want to. I wasn't sure how you wanted it to look after two rows so I guessed.

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

public class CustomCellRenderer implements Runnable, ActionListener {
    public static void main(String[] args) {
        SwingUtilities.invokeLater(new CustomCellRenderer());
    }

    JTable table;

    @Override
    public void run() {
        JFrame frame = new JFrame("Custom Cell Renderer");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        table = new JTable(new DefaultTableModel(0, 2) {
            @Override
            public Class<?> getColumnClass(int c) {
                return Object.class;
            }
        });

        class RedYellowRenderer extends DefaultTableCellRenderer {
            RedYellowRenderer() {
                setHorizontalAlignment(CENTER);
            }
            @Override
            public Component getTableCellRendererComponent(
                JTable table, Object value,
                boolean isSelected, boolean hasFocus,
                int row, int column
            ) {
                Component c = super.getTableCellRendererComponent(
                    table, value, isSelected, hasFocus, row, column
                );

                if(row == 0 && table.getRowCount() > 1) {
                    c.setBackground(Color.YELLOW);
                    c.setForeground(Color.BLACK);
                } else {
                    c.setBackground(Color.RED);
                    c.setForeground(Color.WHITE);
                }

                return c;
            }
        }

        table.setDefaultRenderer(Object.class, new RedYellowRenderer());
        table.setTableHeader(null);

        JButton btn = new JButton("Add Row");
        btn.addActionListener(this);

        JToolBar bar = new JToolBar();
        bar.setFloatable(false);
        bar.add(btn);

        JPanel content = new JPanel(new BorderLayout());
        content.add(bar, BorderLayout.NORTH);
        content.add(new JScrollPane(table), BorderLayout.CENTER);

        frame.setContentPane(content);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    @Override
    public void actionPerformed(ActionEvent ae) {
        int nextRow = table.getRowCount();
        DefaultTableModel model = (DefaultTableModel)table.getModel();
        model.addRow(new Object[] { "NAME" + nextRow, "SPORT" + nextRow });
    }
}