import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.LayoutManager;
import java.awt.Paint;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.plaf.PanelUI;


@SuppressWarnings("serial")
public class ColorfulPanel extends JPanel {

    private Color color1 = new Color(116, 149, 226);
    private Color color2 = new Color(199, 212, 247);

    private void init() {
        setUI(new PanelUI() {
            public void update(Graphics g, JComponent c) {
                if (c.isOpaque()) {
                    Graphics2D g2 = (Graphics2D) g;
                    Paint old = g2.getPaint();
                    int w = c.getWidth();
                    int h = c.getHeight();
                    g2.setPaint(new GradientPaint(0, 0, color1, w, h , color2));
                    g2.fillRect(0, 0, w, h);
                    g2.setPaint(old);
                }
                paint(g, c);
            }
        });
    }

    public ColorfulPanel() {
        super();
        init();
    }

    public ColorfulPanel(Color lt, Color rb) {
        super();
        if (lt != null) this.color1 = lt;
        if (rb != null) this.color2 = rb;
        init();
    }

    public ColorfulPanel(boolean isDoubleBuffered) {
        super(isDoubleBuffered);
        init();
    }

    public ColorfulPanel(LayoutManager layout) {
        super(layout);
        init();
    }

    public ColorfulPanel(LayoutManager layout, boolean isDoubleBuffered) {
        super(layout, isDoubleBuffered);
        init();
    }

    public Color getColor1() {
        return this.color1;
    }

    public void setColor1(Color c) {
        if (c != null) this.color1 = c;
    }

    public Color getColor2() {
        return this.color2;
    }

    public void setColor2(Color c) {
        if (c != null) this.color2 = c;
    }

    public static void main(String[] args) {
        JFrame frm = new JFrame("Test");
        frm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frm.getContentPane().add(new ColorfulPanel(), BorderLayout.CENTER);
        frm.setBounds(60, 60, 260, 260);
        frm.setVisible(true);
    }

}