repaint swing button with different gradient

The easiest approach is to use setPressedIcon(), but you can also override paint() in the ButtonUI delegate, as shown in this example.

And another amusing example:

import java.util.List;
import javax.swing.*;
import javax.swing.plaf.ColorUIResource;

public class GradieltButton {

    public static void main(String[] args) {
        Object grad = UIManager.get("Button.gradient");
        List gradient;
        if (grad instanceof List) {
            gradient = (List) grad;
            System.out.println(gradient.get(0));
            System.out.println(gradient.get(1));
            System.out.println(gradient.get(2));
            System.out.println(gradient.get(3));
            System.out.println(gradient.get(4));
            //gradient.set(2, new ColorUIResource(Color.blue));
            //gradient.set(3, new ColorUIResource(Color.YELLOW));
            //gradient.set(4, new ColorUIResource(Color.GREEN));
            //gradient.set(2, new ColorUIResource(221, 232, 243));//origal Color
            //gradient.set(2, new ColorUIResource(255, 255, 255));//origal Color
            //gradient.set(2, new ColorUIResource(184, 207, 229));//origal Color
            gradient.set(2, new ColorUIResource(190, 230, 240));
            gradient.set(3, new ColorUIResource(240, 240, 240));
            gradient.set(4, new ColorUIResource(180, 200, 220));
            //UIManager.put("Button.background", Color.pink);
        }
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                new GradieltButton().makeUI();
            }
        });
    }

    public void makeUI() {
        JButton button = new JButton("Click");
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(button);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
}

@ShaggyInjun wrote For some reason my UIManager.get("Button.gradient") returns a null. Would you know why ? I know I am using MetalTheme.

this Key in UIManager returns ColorUIResource (more in UIManagerDefaults by @camickr)

[0.3, 0.0, javax.swing.plaf.ColorUIResource[r=221,g=232,b=243], javax.swing.plaf.ColorUIResource[r=255,g=255,b=255], javax.swing.plaf.ColorUIResource[r=184,g=207,b=229]]

is required to use ColorUIResource instead of Gradient, Button.gradient returns arrays of Colors and Insets == ColorUIResource