loading an image from resources folder using relative path - java

How to set the images in background of shell using relative path. I have image which resides in folder "res". I am adding screen shot here, just you to have better understanding of 'directory structure' as well as my question(in case if it seemed little ambiguous to you). Any suggestion and help will be appreciated.

The SplashWindow.jpg is placed next to the class notDltNow which you specify as the reference for relative paths, so you can simply write:
shell.setBackgroundImage(SWTResourceManager.getImage(
notDltNow.class, "SplashWindow.jpg"));
It is also a good idea to put resources inside the src folder so when you export your code e.g. into a jar, the resources will also be exported and still available to the code without additional hassle.

In order to read your images from resources folder, you need to :
add res folder to classpath
locate file absolutely, i.e. "/res/SplashWindow.jpg"
Hope this helps

Related

Referencing an image inside a jar file when running junit

I have been playing with the idea of using ImageMagic (im4java) to do a comparison of known good page renders against stored good pages.
I have got this working on a test site, but all my images (good, bad and differrent) are stored in my c:\temp folder. I have been toying with the idea of having the "expected" images kept inside the project folder structure, so when the project is checked out, the expected images are there.
(not saying this is a great solution, this is just something I have been playing with.)
So my test is stored in
/src/test/java/my.screen.test/compareTest.java
and I have my "expected" image in
/masterImages/test.png
I have tried various ways to reference this:
I included masterImages in the build path and then tried to use
InputStream input = getClass().getResourceAsStream("/masterImages/googleHomePage1.png");
(I then thought I could simply use input.toString() to pass into im4java - but the InputStream gave me nullpointer exception)
I also tried removing the masterImages from the buildpath and trying it that way.
I have also tried
String path = getClass().getClassLoader().getResource("masterImages/googleHomePage1.png").toString();
Again, null pointer. I know there is something stupid I am not seeing here, like I said this started as me playing but it's now annoying me why I can't get it to work.
Any insights into what I am missing greatly appreciated.
From - In java, how do you retrieve images from a jar file?
It is indeed simple: you use the various getResource() methods in java.lang.Class and java.lang.ClassLoader. For example, in your app, you could just write
treeURL = getClass().getResource("/images/tree.png");
This would find the file in an images directory at the root of the jar file. The nice thing about the getResource() methods is that they work whether the files are in a jar or not -- if the images directory is a real directory on disk, this will still work (as long as the parent of images is part of your class path.)
Thanks to all. I think I have this sorted. Turns out I had to add the folder containing the image to the classpath - I wrongly assumed that as I had masterImages/otherFolderName that any file inside otherFolderName would be included if I included masterImages. Turns out this is not the case (at least for me.)

Why does an image path no longer work once I compile my java files into a jar file?

I have a relatively basic java program which uses a system tray icon. The path I was using while writing the code is as follows "../images/logo.png". However, when I compile it into a jar file, the image does not show up in the system tray. Instead, if I change the path to "./images/logo.png", then the image shows up in the system tray when it's in the jar file form, but not while I'm testing.
It's not a major issue. However, I am curious to know why this inconsistency occurs.
When you package your program into a .jar file, your build is most likely copying the image into the same directory as the .jar file. However, when debugging in your ide, your image file lies one directory below.
Another possibility is that you are simply setting your Working Directly differently in the two scenarios.
Incidentally, you might be interested in embedding the image in your jar file, see:
https://stackoverflow.com/a/1096491/24954
This answer depends on two things. If the image file is embedded or not.
Embedded Resource
Once you have Jar'ed your application and the images are emebbed inside the application, normal file access methods will no longer work.
Trying to do something like...
new ImageIcon("../images/logo.png");
or
new File("../images/logo.png");
Won't work. This is because the resource is no longer a file within the context of the file system (it's actually a Zip entry in the Jar).
Instead, you need to use Class#getResource which will return a URL to the embedded resource.
new ImageIcon(getClass().getResource("../images/logo.png"));
Will work better. In general though, it is recommended to use an absolute path to the resources new ImageIcon(getClass().getResource("/images/logo.png")); as it's generally more difficult to break (IMHO)
External Resource
The path to the image is relative to the execution point of the application.
In development, you may have had to move up a directory (out of the src folder presumably) to find the image resource. This will mean that you will need to store you Jar file in a folder that would require it step up one level before it could find the image resource.
If you can, it's generally better to embedded the resource within the Jar where possible. It makes it easier to deploy as you reduce the number of files you need to package and makes it (a little) harder for the user to mess with it ;)

Find a resource both in .jar and eclipse with the same String computation

I want to get the path to a resource for ImageIO to read out a BufferedImage from some .png s.
While developing the project I use a relative path to "/bin/stuff/icons/image.png" , but this will definetly not work when I put everything together into a .jar file, so I need a way to get the path to these resources both while testing in eclipse and when later running it within a .jar .
After a lot of trying out both finding the file and getting the input stream to the file I came to the conclusion that this approach works every time:
InputStream in = ClassLoader.getSystemClassLoader().getResourceAsStream(path)
BufferedImage image = ImageIO.read(in)
Where path is
"projectName/resourceFolder/" + nameOfResource.stuff
as found in the src directory of the eclipse project.
E.g.
"myProject/images/icon.png"
When getting only the resource and then getting the path of the resource to link to a file, you will get FileNotFoundExceptions when using a .jar (but not while testing with eclipse, so one should be warned to think that his code works).
And - no - I don't save images in the bin/ - but they are copied to this directory and thus I find them there while testing. Now everything seems to be working.
Don't put anything under the bin directory in Eclipse: if you run a clean on the project it will be erased.
What you can do is to define a new source folder like resources, and put the image there. This way it will be automatically copied to the bin folder.
If you include the resources folder into the Jar, it will be available in both environments by using something like:
ImageIO.read( getClass().getResource("/image.png") )
PS: You can evade using a different resources folder but mixing the sources and images will quickly pollute your source folder.

Why is my BufferedImage receiving a null value from ImageIO.read()

BufferedImage = ImageIO.read(getClass().getResourceAsStream("/Images/player.gif"));
First of all, yes I did add the image folder to my classpath.
For this I receive the error java.lang.IllegalArgumentException: input == null!
I don't understand why the above code doesn't work. From everything I read, I don't see why it wouldn't. I've been told I should be using FileInputStream instead of GetResourceAsStream, but, as I just said, I don't see why. I've read documentation on the methods and various guides and this seems like it would work.
Edit: Okay, trying to clear some things up with regards to what I have in the classpath.
This is a project created in Eclipse. Everything is in the project folder DreamGame, including the "Images" folder. DreamGame is, of course, in the classpath. I know this works because I'm reading a text file in /Images with info on the gif earlier on in the code.
So I have: /DreamGame/Images/player.gif
Edit 2: The line that's currently in the original post is all that's being passed; no /DreamGame/Images/player.gif, just /Images/player.gif. This is from a method in the class ImagesLoader which is called when an object from PlayerSprite is created. The main class is DreamGame. I'm running the code right from Eclipse using the Run option with no special parameters
Trying to figure out how to find which class loader is loading the class. Sorry, compared to most people I'm pretty new at this.
Okay, this is what getClassLoader() gets me: sun.misc.Launcher$AppClassLoader#4ba778
getClass().getResource(getClass().getName() + ".class") returns /home/gixugif/Documents/projects/DreamGame/bin/ImagesLoader.class
The image file is being put in bin as well. To double check I deleted the file from bin, cleaned the project, and ran it. Still having the same problem, and the image file is back in bin
Basically, Class.getResourceAsStream doesn't do what you think it does.
It tries to get a resource relative to that class's classloader - so unless you have a classloader with your filesystem root directory as its root, that won't find the file you're after.
It sounds like you should quite possibly really have something like:
BufferedImage = ImageIO.read(getClass().getResourceAsStream("/Images/player.gif"))
(EDIT: The original code shown was different, and had a full file system path.)
and you make sure that the images are copied into an appropriate place for the classloader of the current class to pick up the Images directory. When you package it into a jar file, you'd want the Images directory in there too.
EDIT: This bit may be the problem:
First of all, yes I did add the image folder to my classpath.
The images folder shouldn't be in the classpath - the parent of the Images folder should be, so that then when the classloader looks for an Images directory, it will find it under its root.
If you use resourceAsStream "/" referes to the root of the classpath entry, not to the root of the file system. looking at the path you are using this might be the reason.
If you load something from some home path you probably should use a FileInputStream. getResourceAsStream is for stuff that you deploy with your app.

Accessing images in Java ME

I used following code to access an image from "res" folder with NetBeans
imgWelcome = Image.createImage("/cover.png");
img = new ImageItem(null, imgWelcome, ImageItem.LAYOUT_CENTER, "");
Though the resource is not getting detected and i keep on getting NullPointerException. As weird as it sounds, exactly same technique worked in my previous program.
What am I doing wrong here?
P.S. I've double checked that the file exists in the res folder
There might be many reasons for this, but I have found that most of the time, it is due to how the project is built. Some build scripts include the resources in the res/ folder as top-level files, and some include that folder as a folder in the jar file.
What I have always done to troubleshoot is to rename the jar output to zip and look inside. If the image files are contained in a folder then you should address them as such.
Your code will not find cover.png if it is in the /res folder.
Inspect the contents of your jar using 7-Zip or similar, ensure the image really is in the /res folder, then replace the first line with imgWelcome = Image.createImage("/res/cover.png");.
Oh wow.. this was because .png was not supported by my emulator. And what all I tried :(

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