I am developing a Java application which displays a big amount of images. The problem is I can't figure out how to make Java find these images.
I have followed several tutorials and answers here at Stackoverflow, but I still haven't managed to find a solution that works regardless of OS (Linux or Windows) and running method (embedded on eclipse or exported jar file). This might be due to the fact that I am still a newbie, though.
I have created a class, which I call myIcon and through this class I mean to access all of these images. In the following code, I want to pass the string "resources/icon/image.gif" to the function getIconPath. The output should be a ImageIcon of this image, since this file exists. Despite that, if I pass to this function the path to an image that doesn't exist, null should be returned. In this case, my application will display a default image (a red x).
public class MyIcon {
// some other functions and properties
private static final ImageIcon getIconPath(String path) {
File f = new File(path);
if (f.exists()) {
return new ImageIcon(path, "");
} else {
return null;
}
}
}
The resources folder is a sibling to the src folder in my directory structure. That is, both resources and src are subfolders of the root directory.
When I run the code above, no image is ever found. The default image is thus always displayed and getIconPath returns null.
I am also aware of the getResource method of ClassLoader, but I still don't really understand how these things should be used.
While running in eclipse, you should print out f.getAbsolutePath(). It probably doesn't point to your file. More generally, you want to access the file as a resource. See:
https://docs.oracle.com/javase/tutorial/deployment/webstart/retrievingResources.html
There are two parts to this - making sure that when you build a jar, the images are part of it, and accessing a resource within the jar.
For the first part, I am guessing that whatever you're using to build a jar, it will put your images into the META-INF folder, which should work without too much issue (if its not there, or in with the Java class/source in the generated jar, that might cause the lookup to fail)
There is another Stack Overflow Post for the second part. The key is to make sure the images you want to load are on the classpath.
Hope this helps!
If resources is in classpath, you can find for the image at classpath, using getResource(String name) or getResourceAsStream(String name).
However, in a simple Java Project, even adding resources to build path, like this:
it will just put the folder content, in other words, just icon/..., to bin folder, something like this:
So, since resources isn't in classpath, just icon, to retrieve the images, you'll need to inform as path only /icon/image.gif, like this:
URL url = YourClass.class.getResource("/icon/image.gif");
ImageIcon icon = new ImageIcon(url);
Related
I'm working on a java project and made it into an executable jar. In the jar, all the correct files are included, but when running the jar, the images don't display.
When I run the program from command line, the program is able to display everything correctly.
I believe the issue might be because of how I set up the filepaths in the code?
Here's an example of my setup:
private static String imgPath;
...
imgPath = String.format("img%d.gif", value);
...
public static ImageIcon getImageIcon() {
ImageIcon ii = new ImageIcon("content/dice/" + imgPath);
return ii;
}
//getImageIcon() is later called by another class
This setup works unless I try to run the program from an executable jar. So my question is how do I get it to work from a jar?
The first mistake is assuming there is a file system (directories & such) inside a Jar. There are paths to resources that might look like directories & files, but no directories or files as such.
Application resources will become embedded resources by the time of deployment, so it is wise to start accessing them as if they were, right now. An embedded-resource must be accessed by URL rather than file. See the info. page for embedded resource for how to form the URL.
Trying to read an image into java, currently what I have to do is this:
Image img = new Image("file:E:/Javaworkspace/Project/src/resource/image.png");
However, I am not the only one going to be working on that project and this path works only in my machine. I did try
Image img = new Image("file:/resource/image.png")
but this leads to FileNotFound. I don't know what this thing is called in English, I hope you understand what I am trying to convey here.
EDIT:
I added the folder "resource" via Build Path now and am trying to get input stream as such:
ImageView imgView = new ImageView(new Image(this.getClass().getResourceAsStream("/resource/image.png")));
Needless to say, I get a NullPointerException, which according to the documentation, occurs when the path doesn't exist. How can it not exist after I specifically created it via Build Path, it exists in CLASSPATH. (Yes, the file is there too or can I not simply copy it into the folder? )
Place the image inside the project folder rather than using file system to access the file. Then you can use this:
Image image = ImageIO.read(getClass().getResourceAsStream("/resource/image.png"));
to get the image file where ever required by anyone.
I believe you can always try user.home but then if one person updates an image or adds one it won't update for you.
Image img = this.getClass().getResource("/resource/image.png");
Probably messed up parentheses
Also make sure you have folder "resource" in right folder (most likely same folder src and out are in
Every time I run the exported .jar file, that contains a JFrame with an image as its icon, the file doesn't run, unless I extract the file. In the compiler it is running. I dont want to make a launcher that saves both, the resources package and the jar file, in a directory.
"Why my Jar doesn't run unless I extract files?"
This seems to be the behavior of using File to your resources. Take for example
File file = new File("resources/image.png");
Image image = ImagIO.read(file);
And you project structure (Note the resources should actually be in the src, so that it builds into the jar automatically - unless you configure it differently. But for the sake of this argument, let's say you do confgigure it where resources is built to the jar)
C:\
Project
resources\image.png
Some examination:
Run from IDE - WORKS! Why? Using File looks for files on the file system. Using a relative path, the search will begin from the "working directory", which in the case of the IDE in generally the project root. So "resources/image.png" is a valid path, relative to ProjectRoot
Build jar, say it ends up in a dist dir in the project. This is what it looks like
ProjectRoot
dist
ProjectRoot.jar
Now for the sake of this argument (and is actually the correct way), let's try and print the URL of the resource in out program, so that when you run the jar, it prints out the URL of the file
URL url = Test.class.getResource("/resources/image.png");
System.out.println(url.toString());
When we run the jar C:\ProjectRoot\dist> java -jar ProjectRoot.jar We will see the print out C:\ProjectRoot\dist\ProjectRoot.jar!\resources\image.png. You can obviously see even though the current working directory is the location of the jar, the paths no longer match, with the added jar ProjectRoot.jar! location.
So why does it work when we extract it. Well when you extract it, then the path is correct
C:\ProjectRoot
dist
resources/image.png // from extracted jar
ProjectRoot.jar
When you run from the C:\ProjectRoot\dist >, the resource dir is where is should be.
Ok enough with the explanation.
For this reason, when you want to read embedded resources, they should be read from an URL as Andrew Thompson mentioned. This url should be relative to the class calling it, or the class loader. Here are a couple different ways:
As shown already
URL url = getClass().getResource("/resources/image.png");
Notice the /. This will bring us to the root of the classpath, where the resources dir will be. URL can be passed to many constructors, like ImageIcon(URL) or `ImageI.read(URL)
You can use:
InputStream is = getClass().getResourceAsStream("/resources/image.png");
Which will use an URL under the hood. You can use InputStream with many constructors also.
There's also ways to use the class loader, which will start at the root, so you don't need the /
URL url = getClass().getClassLoader().getResource("resources/image.png");
So there are a few ways you can go about it. But in general, reading File with hard coded string paths is never a good idea, when using embedded resources. It's possible to obtain the path dynamically so you can use File, but you will still need to use one of the aforementioned techniques, which unless you really need a File would be pointless, as you can do what you need with the InputStream or URL
To make a long story short
This would work
ProjectRoot
src\resources\image.png
URL url = getClass().getResource("/resources/image.png");
Image image = ImageIO.read(url);
I want to set icon to my JFrame. I do the following:
Image icon = Toolkit.getDefaultToolkit().getImage("src/images/icon.jpg");
this.setIconImage(icon);
It works fine when I run this code from netbeans, but when I try to run this code from jar file, images are not shown in my JFrame. I have tried to load images as resources:
this.setIconImage(Toolkit.getDefaultToolkit().getImage(getClass().getResource("/src/images/icon.jpg")));
but when I run this code it fails with NullPointerException
Uncaught error fetching image:
java.lang.NullPointerException
at sun.awt.image.URLImageSource.getConnection(URLImageSource.java:99)
at sun.awt.image.URLImageSource.getDecoder(URLImageSource.java:113)
at sun.awt.image.InputStreamImageSource.doFetch(InputStreamImageSource.java:240)
at sun.awt.image.ImageFetcher.fetchloop(ImageFetcher.java:172)
at sun.awt.image.ImageFetcher.run(ImageFetcher.java:136)
How can I do this work?
edit:
Thanks to all,
the problem was solved by specifying image as
Toolkit.getDefaultToolkit().getImage(getClass().getClassLoader().getResource("images/icon.JPG"))
As for it seems rather weird, and would be better if it was like
this.setIconImage(new ImageIcon(pathToIcon).getImage());
Assuming your JAR file has a top level directory called images, you can use either:
getClass().getResource("/images/icon.jpg") or
getClass().getClassLoader().getResource("images/icon.jpg")
Looking at the source code of URLImageSource, it appears that the reason that getConnection throws an NPE is that it has a null for the url. And that leads me to suspect that
getClass().getResource("/src/images/icon.jpg")
is returning null. It would do that if it could not locate a resource with that pathname.
I bet that the problem is that you've got the path wrong.
To prove / disprove this, you should run jar tvf on the JAR file, and look for the line that matches "icon.jpg". Is the corresponding pathname the same as what you are using? If not, use the pathname from the matching line in the getResource call and it should work. Alternatively, if the file doesn't show up at all, look at the NetBeans build configs that tell it what to put in the JAR file. (I'm not a NetBeans user, so I can't say where you would need to look ...)
If that leads you absolutely nowhere, another possibility is that getClass().getResource(...) is using a classloader that doesn't know about the JAR file containing the image. (This seems pretty improbable to me ...)
getResource() loads a resource from classpath, not an OS path, and the after compilation your classpath will not include the /src folder, but rather just its contents. So you'd better try /images/icon.jpg.
Also you may find this discussion somewhat useful.
This should do it assuming you can import javax.imageio.ImageIO:
Image icon = ImageIO.read(this.getClass().getResource("/src/images/icon.jpg"));
this.setIconImage(icon);
.."/src/images/icon.jpg"..
The '/src' prefix of the address seems suspicious. Many apps. will provide separate 'src' and 'build' directories, but it normally ends up that the 'src' prefix is not used in the resulting Jar. I recommend trying..
.."/images/icon.jpg"..
& also triple checking that the image is in the location of the Jar that the code is expecting to find it.
For this to work, you should access the images from a directory relative to some fixed class.
For example, if the image files are saved in a directory "images" on the same level as the Toolkit.class, then
this.setIconImage(Toolkit.getDefaultToolkit().getImage(Toolkit.class.getResource("images/icon.jpg")));
should work.
You can simply create a package inside the main source, and incluse your images in this package. Then, just call the images in your main class like:
ImageIcon a = new ImageIcon(MainClass.class.getResource("/Package/Image.jpg"));
JFrame f = new JFrame("Edit Configure File");
//Image image = ImageIO.read(getClass().getResource("images/ctx.Icon"));
f.setIconImage(new ImageIcon("images/ctx.PNG").getImage());//this works for me finally
//f.setIconImage(image);
//f.setIconImage(Toolkit.getDefaultToolkit().getImage(getClass().getResource("images/ctx.PNG")));
I know, I know, this has been asked before. But every resource I've looked at uses IconImages while I just have plain Images.
Is there a different solution? Please help as I've been stuck researching and trying to figure this out for days now with no progress.
Image Floor = Toolkit.getDefaultToolkit().getImage("Floor.PNG");
EDIT: If I was to make sure the jar wouldn't compress and I created a seperate directory in the jar for images and put the correct file path, would this code work?
Toolkit#getImage(String s) looks for a file and likely your image is in the Jar and is now a resource not a file. Look to using resources for this.
Note that ImageIO.read(...) can accept an InputStream parameter the Class class has a method, getResourceAsStream(...) which can put the resource into a Stream that ImageIO can read. Give that a try.
Also, are you getting any error messages when you try what you're doing?
Make sure you know what your current directory is, and how it relates to the position of the files in your jar.
Here's how I would handle it.
1) Require there to be a file called "images.txt" in the directory with your jar (or bundle it into the jar.)
2) Make a file called "images.txt" with a format like `FLOOR:C:\\images\\floor.png`
3) Load this file into memory on load.
4) Load your images based on the entries in the file
This will give you the advantage of changing your images without changing your code if it's defined outside the jar :)
It's not loading because you're not putting the path to the images in the declaration. It expects the images to be wherever the jar is (notice there's no directories there)
You need to offload the definition of the file names to a file, or at the very least guarantee the relative position of the files.
Another good option is to put the images in the jar itself, say in an img directory, and reference them there. But then changes to the images require a new jar, which may not be desired for development purposes.
The getImage call is looking in the file system working directory, not inside the Jar file. This is why the jar file loads the images successfully when they are placed in the same directory outside the jar file. If the images are bundled in the jar file, they are no longer file system files to be accessed, but rather Jar file resources. There is a different way to load these, but sorry, I don't know it off the top of my head.
Check the extension of files. I had this problem because the extension was "PNG", when I changed it to "png", everything was ok.
You can't expect a JAR file to magically know where your images are. If you put a JAR file alone on the desktop, it's going to look for the files on the desktop! The code
getImage("Floor.png")
searches the current directory of the JAR (or source project) by default and you'd expect that if the JAR was in the same directory, it would work. If the JAR is on the desktop how does it know where Floor.png is? Of course, you can specify a hard-coded path
getImage("C:\Some Folder Path\Floor.png")
but then Floor.png has to be in C:\Some Folder Path\ for the JAR to work properly.
It sounds like what you really want to do is keep the images in the JAR file (which acts like a ZIP file). The tutorial on doing that is here:
http://download.oracle.com/javase/tutorial/uiswing/components/icon.html#getresource
And I know for ImageIcon you use: new javax.swing.ImageIcon(getClass().getResource("myimage.jpeg") but I have not found anything similar for plain Image.
<head-desk /> You should really get into reading the JavaDocs. Otherwise you are 'coding by magic'. Which generally won't work.
URL urlToImage = getClass().getResource("myimage.jpeg");
// If you need to support Java 1.3
Image image = Toolkit.getDefaultToolKit().getImage(urlToImage);
// If your users have dragged their JRE into this millennium
BufferedImage bufferedImage = ImageIO.read(urlToImage);