How to call public function within the file in Java?

Question

I tried to change the picture in this code. I tried to call the public function, and able to load when I want to call them out. I wanted to know how to do this, so that way I can put them in the if statement, while loop, or case statement.

In this code, I called a public function:

test chill = new chill();

import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.io.*;
import javax.imageio.*;
import javax.swing.*;

public class test extends Component {

    BufferedImage img;
    BufferedImage img1;

    public void paint(Graphics g) {
        g.drawImage(img, 0, 0, null);
        g.drawImage(img1,0,0,null);
    }

    public test() {
       try {
           img = ImageIO.read(new File("smile.png"));
       } catch (IOException e) {
       }

    }
    public chill() {
       try {
           img1 = ImageIO.read(new File("chill.png"));
       } catch (IOException e) {
       }

    }
//img1= ImageIO.read(new File("chill.png"));

    public Dimension getPreferredSize() {
        if (img == null) {
             return new Dimension(100,100);
        } else {
           return new Dimension(img.getWidth(null), img.getHeight(null));
       }
    }

    public static void main(String[] args) {

        JFrame f = new JFrame("Load Image Sample");

        f.addWindowListener(new WindowAdapter(){
                public void windowClosing(WindowEvent e) {
                    System.exit(0);
                }
            });

        test chill = new chill();

        f.add(new test());
        f.pack();
        f.setVisible(true);
    }
}

What did I do wrong in this? If you have a website that explains about it, please post it on here! Thanks a tons!

This program is something that I do for fun.

Answer 1

First, the class should start with a capital letter (by convention). Second

test chill = new chill();

should be

test chill = new test();

Because chill is the variable name, and test is the class. Also, that's a constructor (not a method). And, you can't have a chill constructor in test class.

// public chill() {
//   try {
//       img1 = ImageIO.read(new File("chill.png"));
//   } catch (IOException e) {
//   }
// }

You could have a chill method

public void chill() {
   try {
       img1 = ImageIO.read(new File("chill.png"));
   } catch (IOException e) {
   }
}

And then

new test().chill();

would work.