How to change a JButton color on mouse pressed?

The problem is caused by the fact that a JButton has its content area filled by default and that the Metal L&F will automatically fill it with its internal chosen color when button is pressed.

Best thing to do, is to extend JButton to create your own button, disable content area filled, and paint yourself the background of the button.

Here is a small demo for that (not sure it works on other L&F, even pretty sure it does not):

import java.awt.Color;
import java.awt.Graphics;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.SwingConstants;
import javax.swing.SwingUtilities;

public class TestButton {

    class MyButton extends JButton {

        private Color hoverBackgroundColor;
        private Color pressedBackgroundColor;

        public MyButton() {
            this(null);
        }

        public MyButton(String text) {
            super(text);
            super.setContentAreaFilled(false);
        }

        @Override
        protected void paintComponent(Graphics g) {
            if (getModel().isPressed()) {
                g.setColor(pressedBackgroundColor);
            } else if (getModel().isRollover()) {
                g.setColor(hoverBackgroundColor);
            } else {
                g.setColor(getBackground());
            }
            g.fillRect(0, 0, getWidth(), getHeight());
            super.paintComponent(g);
        }

        @Override
        public void setContentAreaFilled(boolean b) {
        }

        public Color getHoverBackgroundColor() {
            return hoverBackgroundColor;
        }

        public void setHoverBackgroundColor(Color hoverBackgroundColor) {
            this.hoverBackgroundColor = hoverBackgroundColor;
        }

        public Color getPressedBackgroundColor() {
            return pressedBackgroundColor;
        }

        public void setPressedBackgroundColor(Color pressedBackgroundColor) {
            this.pressedBackgroundColor = pressedBackgroundColor;
        }
    }

    protected void createAndShowGUI() {
        JFrame frame = new JFrame("Test button");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        final MyButton btnSave = new MyButton("Save");
        btnSave.setForeground(new Color(0, 135, 200).brighter());
        btnSave.setHorizontalTextPosition(SwingConstants.CENTER);
        btnSave.setBorder(null);
        btnSave.setBackground(new Color(3, 59, 90));
        btnSave.setHoverBackgroundColor(new Color(3, 59, 90).brighter());
        btnSave.setPressedBackgroundColor(Color.PINK);
        frame.add(btnSave);
        frame.setSize(200, 200);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new TestButton().createAndShowGUI();
            }
        });

    }

}