I've been blasting through the Java Swing tutorials on zetcode.com
I've made it all the way to Basic Swing Components II, the JTextPane component.
In this example, an HTML document is loaded into memory and placed into the textpane.
In order to find the file, zetcode.com uses:
String cd = System.getProperty("user.dir") + "/";
textPane.setPage("File:///" + cd + "test.html");
My IDE of choice is Eclipse Kepler.
I have written the code for this example's class and created the HTML document exactly as zetcode.com has shown on the page. I have placed the HTML file in the same source folder and package as the class which uses it.
But when I run the code, I hear a Windows system error sound and the JFrame pops up without any text inside the textpane.
EDIT 01:
I've named the package "com/zetcode/swingtutorial/basiccomponents/".
I've tried using getClass.getResource("/com/zetcode/swingtutorial/basiccomponents/test.html")
and I figure I must have typed this correctly because I do not get an IOException.
EDIT 02:
Here's another interesting thing:
In zetcode's system, they've used "File:///", which caused Windows to play an error sound.
But when I tried "File://", no error sound plays. D'you think that was just a typo on their part?
Either way, my html doc still isn't displayed on the pane. :S
Do you know what I could be doing wrong?
Many thanks for your help!
Try this:
textPane.setPage(YourClass.class.getResource("test.html"));
If its in package
textPane.setPage(YourClass.class.getResource("/packagename/test.html"));
System.getProperty("user.dir");
Gives you the root context location or the project location folder or you can say the current directory when JVM was started
Accordingly give the path or alternately
Try loading this way
String pathOfHtmlFile = Thread.currentThread().getContextClassLoader()
.getResource("yourHtmlFile").getPath();
textPane.setPage(pathOfHtmlFile);
provided the file is in the classpath.
System.getProperty("user.dir")
Returns the "working folder" from which the application was launched. In Eclipse I believe the working directory is the top level project folder (not in src) or it's in the folder that contains the compiled .class files. Try copying the file to those folders and see when it works.
Related
I tried to create an InputStream pointing at an .ico file, which is in a directory in the src directory. I also create an InputStream for a different jar file in my src.
InputStream inIco = Installer.class.getResourceAsStream("/res/" + iconName + ".ico");
InputStream inApp = Installer.class.getResourceAsStream("/res/" + applicationName + ".jar");
that is how I tried to load it. The inputstream for the jar file works, but the other one is null.
Edit: Sorry for the confusion guys. I didn't build the jar, I just ran it from my editor, which obviously gives me different results, now it is working. Thanks for your answers.
getResourceAsStream (gRAS) loads from the same place java loads class files. That's great - it means you can ship your app as a jar and put these resources inside. If it's not working for you, you've misconfigured your build. Specifically, java is first going to determine the classpath root of your Installer.class file and looks there. If you're not sure what that is, run this code:
System.out.println(Installer.class.getResource("Installer.class"));
which will print something like jar:file:/Users/carlos/projects/FooBar/dist/foobar.jar!com/foo/Installer.class
and this tells you that gRAS is going to look in that foobar.jar file.
From there, the resource is loaded relatively to the root (because of that leading slash): Within that jar, it will look for /res/app.ico. Without it, it loads relative to the same dir/package of Installer class (in this example above, gRAS("hello.txt") is the same as gRAS("/com/foo/hello.txt").
To make this work out, your build system is responsible. For maven and gradle, have src/main/java/com/foo/Installer.java along with src/main/resources/res/icon.ico and all should be well. If this is not working out, explain how you've set up your environment because something is misconfigured if this isn't working. If you're using another build tool (such as perhaps ant, sbt, or relying on your IDE to take care of it), name the tool and perhaps we can help address the misconfiguration.
For some unusual reason, when I am using FileWriter for Java Netbean, the file gets written into this directory:
C:\Users\myname\AppData\Roaming\NetBeans\7.2\config\GF3\domain1
rather than to my working directory, which is at the desktop.
I used this code to check my User Directory, and it returns this:
System.out.println(System.getProperty("user.dir"));
INFO: C:\Users\myname\AppData\Roaming\NetBeans\7.2\config\GF3\domain1
which is obviously NOT my working directory where my source code is. I thought I could have accidentally configured Netbeans to change the directory, but I checked through NetBeans menu and can't figure out how to undo this.
I have never had this problem before in my previous projects. As simple as the following code, the file should appear in my working directory.
File file = new File("myFile.xml");
Instead now I'm being forced to enter the path name to make the file save into my working directory, which is not going to be dynamic if I change computer.
String dir = "C:\\Users\\myname\\Desktop\\Assignment\\IRAssignmentJ\\";
File file = new File(dir + "myFile.xml");
Please enlighten me how do I solve this.
rather than to my working directory, which is at the desktop
No it isn't. The current working directory is whereever the file got saved, by definition. If Netbeans chooses to change directory to where it was saved, there's nothing you can do about it. If you want it in your home directory, there is a system property for that. If you want it saved somewhere else, use a full pathname.
But the behaviour of the application under Netbeans is of little interest. What matters is when you run it as though standalone, like a customer would.
I am making an application that searches the screen for a specific image. I read the picture (file) I am scanning for and convert it to a buffered image, then to an int[] so I can process it faster. I also use the robot class to take a screenshot and convert to an int[].
While running code in Eclipse and having the files in the source folder, I don't have any problems. But after exporting my code to a runnable jar file, my scanning methods no longer work. I think it might have something to do with compression because my pictures need to be exactly how they were taken.
The only success I have had with a "finished format" is by exporting the jar normally, and using a folder in the same directory called images to hold the files. Using this code:
File img = new File(System.getProperty("user.dir") + File.separator + "images" + File.separator + "Close.bmp");
When running directly from eclipse I can simply do this:
File img = new File(src/Close.bmp);
Any suggestions? Maybe some tips/settings on exporting jars?
You have various options:
probably the easiest is to put the image in the classpath, i.e. deploy it with your class files, probably within a jar file. The drawback is that you can't replace the image (as long as you don't want your user to fiddle with the classpath)
place it relative to the user.dir as you have done, in this case you need to understand what the user.dir actually is: The working directory from which your application got started. It will differ depending on how you start it.
another option is to use a path relative to user.home which is your home directory.
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.
I was writing a small application and when I tried to create an ImageIcon I always got an exception. The exception was caused by this line of code:
prayerLevel.setIcon(new ImageIcon(getClass().getResource("/icons/icon_prayer.png")));
Now within my program, the folder /icons/ does exist. I don't know if it makes the difference but the class file is within a package, where as the icons folder is within the project folder (when you would see the bin and src folder).
I have looked around for a bit and I couldn't find a solution that could help me solve the problem. Perhaps any of you guys could help?
Edit: someone asked for my folder hierarchy:
I know the class file is not in the same folder as the icons are, but I've made applications where I had to load files from a different folder and doing /folder/ always used to work.
Edit 2:
System.out.println(getClass().getResource("/icons/icon_prayer.png") == null);
Prints true.
I believe the NPE is being thrown from the ImageIcon constructor as getResource is returning null.
Try the following:
getClass().getClassLoader().getResource("/icons/icon_prayer.png")
Or:
ClassLoader.getSystemResource("/icons/icon_prayer.png")
As far as I know getResource() will look into locations of known resources, in other words if the folder /icons/ is not seen as a resource folder it will not as you had expected. There are two ways of going around this as far as I know:
1) Set icons folder as a resource to the application, then you can use getResource() for instance
URL css_url = getClass().getResource("/resource/style.css");
For more info on this option, see http://lj4newbies.blogspot.com/2008/03/using-classgetresource-load-resource.html
2) Get the icon as a regular file without using getResource() method. This is actually adviced in Swing tutorials on Sun/Oracle own documentation .
Generally, applications provide their own set of images used as part
of the application, as is the case
with the images used by many of our
demos. You should use the Class
getResource method to obtain the path
to the image. This allows the
application to verify that the image
is available and to provide sensible
error handling if it is not. When the
image is not part of the application,
getResource should not be used and the
ImageIcon constructor is used
directly. For example:
ImageIcon icon = new
ImageIcon("images/middle.gif",
"a pretty but meaningless splat");
Hope this helps, good luck!
Old thread but since I bumped into a similar problem just now...
I'm using Eclipse and I copied a file to the "resources" folder using system commands (cp). However, eclipse threw a NullPointerException because I didn't refresh the "resources" folder. So the file was there but Eclipse didn't see it.
So in Eclipse: "Package Explorer" -> "resources" -> Mouse right click -> refresh. This fixed it for me.
I added my music, images, etc to a folder added to the build path. Then I just used
URL url="CurrentClass".class.getClassLoader().getResource("media file name not the path");
setIconImage(new ImageIcon(url.getPath()).getImage());
to set the image icon.
The only thing that can throw a NullPointerException in this line of code is the first ., which means that prayerLevel is null.