Develop Reference

Using a pre-loaded icon

I'm using the following to show a cross in a label, that accompanies an if statement.
JLabel.setIcon(new ImageIcon(path + "Resource/cross.png"));
Instead of loading the icon everytime I would prefer to have it imported into my project and call it from there. I know how to import it but how do I modify the line of code above to point to the imported icon.

you can create a static loader methode (in an utility class) and store it there
private static Map<String, Icon> lookUpMap = new HashMap<>();
public static Icon getImageIcon(String res){
Icon icon = lookUpMap.get(res);
if(icon = null){
icon = new ImageIcon(res);
lookUpMap.put(res, icon);
}
return icon;
}
you can access the icons now everywhere
JLabel.setIcon(UtilitClass.getImageIcon(path + "Resource/cross.png));

Why does Image.IO.read() return null in this case?

ImageLoader.java:
public class ImageLoader {
private static BufferedImage image;
public ImageLoader() {
}
public BufferedImage loadImage(String filePath) throws IOException {
image = ImageIO.read(this.getClass().getResourceAsStream(filePath));
return image;
}
public static BufferedImage loadImage(Class classPath, String filePath) throws IOException {
image = ImageIO.read(classPath.getResourceAsStream(filePath));
return image;
}
}
Library.java:
public class Library {
public static final String ResourcePath = "./res/";
public static final String ImagePath = ResourcePath + "Images/";
}
Using ImageLoader.java in three ways:
BufferedImage test = new ImageLoader().loadImage(Library.ImagePath + "imageFile.png");
BufferedImage test = new ImageLoader().loadImage(Main.class, Library.ImagePath + "imageFile.png");
BufferedImage test = new ImageLoader().loadImage("/Images/" + "imageFile.png");
Why is it that only the 3rd case works and the first and second case doesn't? I believe it has something to do with the Library.ImagePath static variable.
If there is a way to fix it, please describe below!

It looks like it has to do with your image path. When you expand the variable, the value is
./res/Images
but from your third example, it looks like the image is in the classpath at
/Images/imageFile.png
So try changing the ImagePath to:
public static final String ImagePath = "/Images/";
The difference here is (Note: I am only guessing from now on), that, in your class path, the images seem to be deployed in the Images folder. On the file system, you seem to have a "res" folder in the root folder where you start your application.
Say your folder structure looks like that:
myProject
+--- res
| +---Images
| \---Texts
\--- src
When you start the application in myProject, and res is on your classpath then the path to images will be different when you load via classpath or via File:
new File("./res/Images/..."); //Relative to the working directory of the app!
classPath.getResourceAsStream("/Images/..."); //Root is your classpath, i.e. "res"!

Path can not be found, creates argument exception

I know what the problem is I just do not know how to fix it. So I have an image that I am trying to render in my program. I use ImageIO to load the image. But it seems to have a problem wit the path I am giving it. I am using NetBeans as my IDE and I dont know if I am saving the image file correctly.
First method:
public void init(){
BufferedImageLoader loader = new BufferedImageLoader();
try{
spriteSheet = loader.loadImage("/sprite_sheet.png");
}catch(IOException e){
e.printStackTrace();
}
SpriteSheet ss = new SpriteSheet(spriteSheet);
player = ss.grabImage(1,1,32,32);
}
the loader BufferedImageLoader class:
public class BufferedImageLoader {
private BufferedImage image;
public BufferedImage loadImage(String path) throws IOException{
image = ImageIO.read(getClass().getResource(path));
return image;
}
}
I have the image saved under a 'res' folder under 'src' folder.
Error:
Exception in thread "Thread-2" java.lang.IllegalArgumentException: input == null!
Thank you.

Why do you need to use getClass().getResource() ?
Most simple usage of ImageIO.read is as follows.
image = ImageIO.read(new File(path));
You may need to add folders to path also.
spriteSheet = loader.loadImage("/src/res/sprite_sheet.png");

Try using an absolute path for your file or if you need a relative check this post (eg assuming you have a res folder under default package did you try "/res/yourfile"

Load Image into JLabel not working

I try to display an image using a JLabel. This is my project navigator:
From SettingsDialog.java I want to display an image using following code:
String path = "/images/sidebar-icon-48.png";
File file = new File(path);
Image image;
try {
image = ImageIO.read(file);
JLabel label = new JLabel(new ImageIcon(image));
header.add(label); // header is a JPanel
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
The code throws an exception: Can't read input file!
Is the path of the image is wrong?

Don't read from a file, read from the class path
image = ImageIO.read(getClass().getResource(path));
-or-
image = ImageIO.read(MyClass.class.getResource(path));
When you use a File object, you're telling the program to read from the file system, which will make your path invalid. The path you are using is correct though, when reading from the class path, as you should be doing.
See the wiki on embedded resource. Also see getResource()
UPDATE Test Run
package org.apache.openoffice.sidebar;
import javax.swing.*;
public class SomeClass {
public SomeClass() {
ImageIcon icon = new ImageIcon(
SomeClass.class.getResource("/images/sidebar-icon-48.png"));
JLabel label = new JLabel(icon);
JFrame frame = new JFrame("Test");
frame.add(label);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable(){
public void run() {
new SomeClass();
}
});
}
}

"/images/sidebar-icon-48.png" is root path. On windows would be c:\images\sidebar-icon-48.png or d:\images\sidebar-icon-48.png depending on current drive (java converts the / to \ - not an issue). Linux images would a child of root /images/sidebar-icon-48.png Need to load relative to class or relative to the jar that had the class (if you do not want to store images inside jar.
In big projects its nice to have images and other resources outside the jar so the jar is smaller and more importantly its easy to change the resources without fiddling with jars/ wars.
Since you seem to be making a add on for open office, you will have to keep everything in jar and so peeskillet answer is right. But make sure your images folder is being packed in the jar. Extract the jar ising the jar command or rename the file to zip and extract.
Or check and fix project settings. How to make a jar in eclipse ... latest one has a wizard that makes an ant script or this SO

try to use this directly :
JLabel label = new JLabel(new ImageIcon(path));
and delete these line :
File file = new File(path);
image = ImageIO.read(file);
if error still exist paste the following error

How do I change the default application icon in Java?

I'm using NetBeans, trying to change the familiar Java coffee cup icon to a png file that I have saved in a resources directory in the jar file. I've found many different web pages that claim they have a solution, but so far none of them work.
Here's what I have at the moment (leaving out the try-catch block):
URL url = new URL("com/xyz/resources/camera.png");
Toolkit kit = Toolkit.getDefaultToolkit();
Image img = kit.createImage(url);
getFrame().setIconImage(img);
The class that contains this code is in the com.xyz package, if that makes any difference. That class also extends JFrame. This code is throwing a MalformedUrlException on the first line.
Anyone have a solution that works?

java.net.URL url = ClassLoader.getSystemResource("com/xyz/resources/camera.png");
May or may not require a '/' at the front of the path.

You can simply go Netbeans, in the design view, go to JFrame property, choose icon image property, Choose Set Form's iconImage property using: "Custom code" and then in the Form.SetIconImage() function put the following code:
Toolkit.getDefaultToolkit().getImage(name_of_your_JFrame.class.getResource("image.png"))
Do not forget to import:
import java.awt.Toolkit;
in the source code!

Or place the image in a location relative to a class and you don't need all that package/path info in the string itself.
com.xyz.SomeClassInThisPackage.class.getResource( "resources/camera.png" );
That way if you move the class to a different package, you dont have to find all the strings, you just move the class and its resources directory.

Try This write after
initcomponents();
setIconImage(Toolkit.getDefaultToolkit().getImage(getClass().getResource("Your image address")));

/** Creates new form Java Program1*/
public Java Program1()
Image im = null;
try {
im = ImageIO.read(getClass().getResource("/image location"));
} catch (IOException ex) {
Logger.getLogger(chat.class.getName()).log(Level.SEVERE, null, ex);
}
setIconImage(im);
This is what I used in the GUI in netbeans and it worked perfectly

In a class that extends a javax.swing.JFrame use method setIconImage.
this.setIconImage(new ImageIcon(getClass().getResource("/resource/icon.png")).getImage());

You should define icons of various size, Windows and Linux distros like Ubuntu use different icons in Taskbar and Alt-Tab.
public static final URL ICON16 = HelperUi.class.getResource("/com/jsql/view/swing/resources/images/software/bug16.png");
public static final URL ICON32 = HelperUi.class.getResource("/com/jsql/view/swing/resources/images/software/bug32.png");
public static final URL ICON96 = HelperUi.class.getResource("/com/jsql/view/swing/resources/images/software/bug96.png");
List<Image> images = new ArrayList<>();
try {
images.add(ImageIO.read(HelperUi.ICON96));
images.add(ImageIO.read(HelperUi.ICON32));
images.add(ImageIO.read(HelperUi.ICON16));
} catch (IOException e) {
LOGGER.error(e, e);
}
// Define a small and large app icon
this.setIconImages(images);

You can try this one, it works just fine :
` ImageIcon icon = new ImageIcon(".//Ressources//User_50.png");
this.setIconImage(icon.getImage());`

inside frame constructor
try{
setIconImage(ImageIO.read(new File("./images/icon.png")));
}
catch (Exception ex){
//do something
}

Example:
URL imageURL = this.getClass().getClassLoader().getResource("Gui/icon/report-go-icon.png");
ImageIcon iChing = new ImageIcon("C:\\Users\\RrezartP\\Documents\\NetBeansProjects\\Inventari\\src\\Gui\\icon\\report-go-icon.png");
btnReport.setIcon(iChing);
System.out.println(imageURL);