java how to add image using getResource()?

Question

I want to add an image to a Jpanel Class, I use the method getResource() but it returns Exception in thread "main" java.lang.IllegalArgumentException: input == null!, because the path into the image folder that i give is not valid, now I want how to get the valid path, I'm aware that maybe it's really easy and it's not a question that I've to ask here but I'm spending a lot of time and trying different path but it doesn't work;

here the Jpanel class

import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;


public class Application extends JPanel  {

    private BufferedImage image;

    public Application() {
          try {
                image = ImageIO.read(getClass().getResource("/ressources/image.png"));
          } catch (IOException ex) {
                System.out.println("problem! image can't be loaded!");
          }
    }

    @Override
    protected void paintComponent(Graphics g)
    {
        super.paintComponent(g);
        g.drawImage(image, 0, 0, null);
    }
}

and here the main class

import javax.swing.*;
//import java.awt.*;

public class mainClass {

        public mainClass () {

            JFrame app = new JFrame();
            app=.setTitle("main window");
            app=.setSize(400, 400);
            app=.setLocationRelativeTo(null);
            app=.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            app=.add(new Application()); 
            app=.setVisible(true);
        }

        public static void main(String[] args) {
            mainClass class = new mainClass();
        }
    }

the error is clearly in the line image = ImageIO.read(getClass().getResource("/ressources/image.png"));

cause the path is not valid, I use a maven project, so the path of this classes is : projectName\src\main\java\application\mainClass.java projectName\src\main\java\application\Application.java

I created a folder "ressources" and i put the image there, here the path projectName\ressources\image.png

thank you.

Answer 1

You need to place your image in src/main/resources/image.png for it to be seen as in the resource root of this project...and watch that spelling of ressource. See http://www.mkyong.com/java/java-read-a-file-from-resources-folder/ for a nice summary of resource loading.

Then this line should work;

image = ImageIO.read(getClass().getClassLoader().getResource("image.png")