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Java Class decorate itself

I think I kind of reinvent caching in Java but have a point I don't get further.
In case the answer is anywhere on Stackoverflow for this issue I might had not understood it when searching or didn't understand the required complexity and searched for a more easy way.
Short what I want to do: call a method on an Object. The object should load a picture and store it as Image. Then it should decorate itself with an Decorator so that called method will next time only return the image with no more IO operations.
My Interace Picture Interafce is simple like this:
import java.awt.*;
public interface PictureInterface {
public Image getImage();
}
My Decorator looks like this:
import java.awt.*;
public class PictureDecorator implements PictureInterface {
private final Picture p;
public PictureDecorator(Picture p){
this.p = p;
}
public Image getImage(){
return this.p.pipeImage();
}
}
It saves a Picture and on getImage() calls pictures pipeImage - the picture "real" getImage().
And last but not least the Picture Class:
import java.awt.Image;
public class Picture implements PictureInterface{
private final String path;
private final Image image;
public Picture(String path){
this.path = path;
}
private void loadImage(){
this.image = /*IO Magic Loading the Image from path*/
}
public Image getImage() {
loadImage();
/*Decorate Yourself with Picture Decorator*/
return /*Decorator.getImage*/;
}
Image pipeImage(){
return this.image;
}
}
If getImage is called I want Picture to Decorate itself and call the Decorators getImage and most importent overwrite its old refference (Java is call by value, this is where i'm stuck atm) so on further getImage Calls the Decorators getImage Method is called.
As a little extra-question I think my access to the mage from Decorator is not best practice, hints welcome ^^
EDIT:
To add a thing: I allready thought if this it not possible: what would be "smarter": go for if(image==NUll) or make a decorateYourself() function where image is loaded and decorator returned in Picture and in Decorator it only returns itself, apply this to the Image var and then call getImage, like:
ImageInterface x = new Image("path);
x = x.decorateYourself()
Image i = x.getImage()
this ways i would only do a method-call to return the decorator itself, but i have to call both methods ...

If getImage is called i want Picture to Decorate itself and call the
Decorators getImage and most importent overwrite its old refference
(Java is call by value, this is where i'm stuck atm) so on further
getImage Calls the Decorators getImage Method is called.
A decorator doesn't work in this way.
With decorator you want to augment or diminish a behavior of an existing class without being invasive for this class : no needed modification.
So the decorator instance decorates an object that has to share with the decorator class a common type and a common method.
Besides I don't think that you need to use a decorator.
Here you don't decorate a picture but you bypass its loading if it was already previously performed.
I think that it would be more suitable to use a proxy that decides whether it must load the resources of get it from the cache.
Don't worry, it doesn't change many things in the classes you have introduced: interface, common method and object wrapping are still required.
In your case PictureInterface is the common type between the proxy class and the proxy subjects classes that provides the common method : getImage().
import java.awt.*;
public interface PictureInterface {
public Image getImage();
}
PictureProxy, a proxy class could implement PictureInterface to act as any PictureInterface instances.
PictureProxy should be responsible to check if it has cached the result of a previous loading of the image. It is the case it returns it. Otherwise it calls getImage() on the Picture instance that holds and it caches the result.
import java.awt.*;
public class PictureProxy implements PictureInterface {
private final Picture p;
private final Image image;
public PictureProxy(Picture p){
this.p = p;
}
public Image getImage(){
if (image != null){
return image;
}
image = p.getImage();
return image;
}
}
And Picture class should not be aware of the proxy when it performs getImage().
It is the proxy class that handles the state of the cache.
import java.awt.Image;
public class Picture implements PictureInterface{
private final String path;
private final Image image;
public Picture(String path){
this.path = path;
}
private void loadImage(){
this.image = /*IO Magic Loading the Image from path*/
}
public Image getImage() {
loadImage();
return image;
}
}
From the client of the classes you could do something like that :
Picture picture = new PictureProxy(new Picture("picturePath"));
Image img = picture.getImage(); // load the image from Picture the first time and get it
Image img = picture.getImage(); // get it from the PictureProxy cache

Java can't instantiate an Image?

So for my 2D game I want to use an image to represent a player but when I try to use an image, it tells me that it couldn't be "instantiated". I don't know what that means:
public class PlayerOne extends Entity{
private Image img = new Image();
[...]
#Override
public void render(Graphics g){
g.drawImage( img , x, y, Color.BLUE, new ImageObserver());
}
}
I tried it in another class with BufferedImages but that somehow doesn't work.
So it can't create Objects of neither Image nor the ImageObserver. Does anyone know a fix for this error ?

You cannot instantiate an abstract class. Please see link.
Following syntax would be operational:
private Image image = new BufferedImage(200,200,BufferedImage.TYPE_INT_RGB);
Also see link for more information on BufferedImage. Additionally, here is a tutorial which ilustrates an example implementation;

You should have an image file (*.png for example ) to start with. Then use
Image img = new ImageIcon("img.png").getImage();

How do I get a path to an image?

I tried to do this:
Path pathForSpriteSheet = Paths.get("/PicFolder/TheSpriteSheet.png");
Then I put it in this method like this:
loadImage(pathForSpriteSheet);
public void loadImage(BufferedImage image){
theImage = image;
}
It says "The method loadImage(BufferedImage) in the type BufferedImageLoader is not applicable for the arguments"

To further what Tom said, you cannot pass a Path variable to the method loadImage when it requires a BufferedImage. What you need to do is create a BufferedImage based off of the path you already have and send that to the method. Something like:
BufferedImage img = ImageIO.read(pathForSpriteSheet.toFile());
loadImage(img);

Change the default Java icon [duplicate]

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);

How to: Make addition to class property within list

I have a List<Presenter> presenterList;
With
public class Presenter(){
String name;
String imageRef; // Filename to be downloaded
Bitmap image;
(etc...)
}
I'm working with AsyncTask & once the image has downloaded, I wish to go through the list and set Image value to the newly download image.
so far i have
Presenter pres = PresenterList.get(Position);
pres.Image = new (Bitmap) downloadedImageFromImageRef;
however i fear that this will not relate to the Image value of the presenter within the list.
How do i refer, or even assign to the specific Presenter attribute within the list?
From working with C (many years ago), i belive somthing like a pointer to the value in which to assign .Image would work
Thank you in advace

Well, if you have C experience, then the thing to know about Java is that it doesn't use pointers, but it does use references. So if I'm understanding your problem correctly, you are already using the Image attribute of a Presenter instance elsewhere and then you want to fill it in later. Assigning pres.Image = new (Bitmap) DownloadedImageFromImageRef; would not work in this case because other objects are looking at a different Bitmap object reference.
What you might need to do is use an observer pattern -- it depends on the details of your problem. Here's an example:
Somewhere in the code I have a class Foo that wants to use the Image property from a Presenter instance. But, since that property isn't set until later, this class wants to be notified when it is ready (it is an observer).
public class Presenter {
String Name;
String ImageRef; // Filename to be downloaded
private Bitmap Image;
private PresenterImageObserver observer;
public void setImageObeserver(PresenterImageObserver pio) {
this.observer = pio;
}
public void setImage(Bitmap b) {
this.Image = b;
this.observer.imageLoaded(b);
}
}
public interface PresenterImageObserver {
public void imageLoaded(Bitmap b);
}
public class Foo implements PresenterImageObserver {
//Foo's constructor. It wants the image from presenter p, when it is ready
public Foo(Presenter p) {
p.setImageObserver(this);
}
public void imageLoaded(Bitmap b) {
//b contains the loaded image and this Foo instance can use it now!
}
}
You'd need to set the image using pres.setImage(new (Bitmap) downloadedImageFromImageRef);.

So you have to find in your list the Presenter for which the correct imageref. You have basically two options.
First, you simply iterate through your list
for (Presenter presenter: presenterList) {
if (presenter.imageref.equals(imageName) {
Presenter.image = new Bitmap(downloadedImage);
break; // found : stop iterations
}
}
Secondly, you can create a HashMap for your presenters, with the imageref as the key :
HashMap<String, Presenter> map = new HashMap<>();
for (Presenter presenter: presenterList) {
map.put(presenter.imageref, presenter);
}
Then, you can directly find the right presenter through map.get(imageName)