CODEWITHSUNDEEP
javaswingcolorsjbuttonactionlistener
JayDP
JayDP

Reputation: 13

How to set JButton to change color gradually when clicked

I wanted to create JButton to change color every time it is clicked but it doesn't change after second click. It is strange because with Random().nextInt(250) instead of i it works. What could be the problem?

Here's the code:



import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Main {

    public static void main(String[] args) {
        JFrame jf = new JFrame();
        jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel jp = new JPanel();
        jp.setLayout(new BorderLayout(100, 100));

        JButton l = new JButton("Hello");
        l.setBackground(new Color(245, 12, 53));
        jp.add(l, BorderLayout.EAST);
        jf.add(jp);
        jf.setSize(200, 200);
        jf.setLocationRelativeTo(null);
        jf.setVisible(true);

        l.addActionListener(new ActionListener() {

            Integer i = new Integer(0);
            Color c = new Color(150, 10, i);

            @Override
            public void actionPerformed(ActionEvent e) {
                // TODO Auto-generated method stub
                if (i < 200) {
                    i += 50;

                    c = new Color(150, 10, i);

                    l.setBackground(c);
                } else
                    i = 0;
            }
        });

    }
    }

Upvotes: 1

Views: 129

Answers (2)

camickr
camickr

Reputation: 324088

Works fine for me.

Although the code should probably be something like:

if (i < 200) 
    i += 50;
else
    i = 0;

c = new Color(150, 10, i);
l.setBackground(c);

Otherwise there will be one click that doesn't change the color.

You may want to consider using HSL Color this will allow you to change the Color in a more meaningful way by either changing the hue of the Color or shade/tone of the Color.

Upvotes: 0

Sweeper
Sweeper

Reputation: 270790

I debugged your code and saw that the value of c change, every time I click the button. The first value is (r=150,g=10,b=50), then turns into (r=150,g=10,b=100), then (r=150,g=10,b=150) etc.

This means that the color is indeed changing. It's just that the difference is too small for you to notice.

So why does random.nextInt work?

With a random value in the blue component. The value can jump very suddenly from 0 to 200. The color difference is so large that your eyes can see it. But with a gradual change of 50 every time, you only notice it the first time.

Just test it with new Color(0, 0, i). I think that will make a bigger difference. It will go from black to blue!

Upvotes: 3

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