I'm relatively new to Java and programming in general, so my question may seem obvious, but I am trying to learn.
To make it short, there are .class files in my source folder.
I work in Eclipse and I'm not sure how they got there. I've always had the output directory in a bin folder rather than the src folder. Based on Windows, those .class files haven't been changed in over a month.
Would anyone suggest removing them to make the work space a little bit neater?
Thanks.
Yes, you can always remove the .class files - Eclipse will just remake them at the right time.
To change where they are stored, right-mouse on your project in the Package Explorer and select Build Path > Configure Build Path. Click on the "Source" tab. The output folder is listed at the bottom of the tab.
Related
Ok the deal is, I've made a small class library (*.Jar file) to help make a more visually organized code and to help with some common tasks.
Before you tell me to go to: Tools > Preferences > Libraries.
I have done that, over and over and over again.. I also tried to manually add it to: C:\Program Files\BlueJ\lib\userlib\"jar file here"
And yes, i did restart BlueJ to load the newly added libraries.
No matter what i seem to try it won't let me import it to my project using the import command, but without it, it just won't compile.
I know i can just add the classes manually, but as the class library slowly grow, so does the effort of adding all the classes in that library.
In advance, thanks for your help and consideration.
If adding your jar file in the Preferences > Libraries tab doesn't work, you can try adding the jar to the "userlib" directory at <bluej-dir>/lib/userlib (where <bluej-dir> is the folder where BlueJ was installed).
A third option you can try is adding your jar file directly to a project by creating a +libs directory inside your project directory and copying the jar to that directory. This has the drawback that you have to manually copy the jar to each project +libs subfolder that needs your library. On the plus side, it allows you to distribute your project (library jars included) just by zipping up the root project directory.
On Windows I create directory named "+libs" on my blueJ project directory,
then add .jar to that directory, and restart blueJ ,
that´s help me, and import after that work fine
Despite the post's oldness for who stumble upon i can say with the newest version of BlueJ (actually 4.1.3) in an old Ubuntu distro(Lucid Lynx aka 10.04LTS) all work as intended per default without any hack
I have a Java JAR file that was developed to run in the browser. It works fine. There doesn't appear to be any sort of build file associated with the source code I've been given and I'm attempting to create a project and/or build script.
The source code references some third party code. What I've done is unzipped the JAR file into a folder that has this structure:
\App\src\com
\App\src\META-INF
\App\src\applet
The "com" folder contains subfolders which contain the .CLASS files for the third party libraries. "applet" contains the .JAVA source code files (one folder, maybe 15 files).
The code appears to be written in 1.4 syntax (I manually attempted to compile some of the .JAVA files and it complained that some things were deprecated and/or required the older version).
I created a Java Project in Eclipse and pointed it to the \App folder. Then I went into the Properties for the project and went to Libraries and and clicked on "Add Class Folder" and added the \App\src\com folder. Then I went to "Order and Export" and moved this to the top. I also set the Java Compiler version to 1.4.
I am getting a large number of compiler errors, all of which seem to stem from the fact that it says it can't resolve an import. This import is the set of .CLASS files contained in the "com" subfolders. The namespace matches the directory structure.
This seems like it should be really straightforward, but I've tried various things and don't seem to be making any progress. Based on what I've read I'm sure it has something to do with the pathing but I'm at a loss at this point on how to fix it.
(I'm sure it goes without saying that I'm not a Java dev.)
Any thoughts or ideas as to where I'm going wrong?
Can you please try to right click on Eclipse's Navigator. Select Import>General>archive file> (Jar file that you want to import).
You should be getting the jar file correctly imported at this point. Do tell me if you face any problems.
This question already has answers here:
Error: Selection does not contain a main type
(24 answers)
Closed 8 years ago.
I am receiving the errors: Editor does not contain main type, or, Selection does not contain main type when I import an archived Java project into Eclipse and try to run it. I have gotten this error on several different operating systems.
Archive Protocol
Export project
General->Archive File
All are selected: project folder, .classpath and .project
[x] save in zip format
[x] create directory structure for files
[x] compress contents of file
A Work Around That May Explain It... but how?!
I notice that when I import an archived project into an existing project (a blank Java project), The folder hierarchy is something like:
Project
src
bin
imported_project
bin
src
actual_code.java
Now, when I try to run actual_code.java, I get the above error. I discovered the following work around: if I drag actual_code.java and drop it into Project->src and then run it, it works.
This is a nice work around. However, I would prefer to be able to run the imported project without moving things around. Any suggestions on how to do this? It seems like it should be a trivial fix--it simply seems like the project isn't importing to where it ought to.
And yes...
I have tried every method I have come across to remedy this. That includes quite a few from this site and others: syntax, libraries, source path, restart eclipse, rearchive, different operating systems, different machines... etc.
The .java files are in the src folder before I archive them, and my build path seems correct.
You could import the archive as a Project instead of as files into a newly created blank project. Use Import > Existing Projects into Workspace. Then, use Select archive file.
You might want to put the src folder of your imported_project in classpath.
Right click on your project -> Properties -> Java Build Path -> Source -> Add Folder
I also faced the same error ajnd after reading above article i just drag/drop my class-file to src and new class-file generated in src is working fine .
I had the same problem after I New/Java Project then pulling src, docs, lib, examples, ... folders. I could not import it as an Eclipse project since the code is not an Eclipse project. The main is right there in the example code, but the IDE would find it.
The solution for me is deleting the project from the IDE, then recreating it with the Eclipse IDE. When recreating, the IDE cached all the sub-folders for me. Also, make sure you add the code onto the Java Build Path as Source using the 'Configure Build Path...' of the project.
Restarting IDE, closing then reopening the file didn't help me.
Although this seems an easy thing I'm not able to find the answer for it.
What I'd like to achieve is simple. I have a folder with java source files and I want to edit them using eclipse within a new project. But at the time of running the application I don't want eclipse to use the workspace project folder as "root", instead it should use the folder with the java source files.
The effect should be like opening the source files with a text editor directly and changing them, but instead this should be done through an eclipse project but still use the original folder to run the application.
I just want to have all the advantages that come from editing source files within an eclipse project instead of using something like notepad++.
I tried linking the source files and changing the relative path to the source directory but it doesn't work. When running the application it needs xml files which exist in the directory but because it's running "from" the eclipse project folder it doesn't find them.
I'm not sure I really understand what you want to do, but sounds like you want to set the run configuration's working directory: Open 'Run Configurations', choose the class containing your main method (or create a new run configuration for that class first if it's not yet there), then specify the Working Directory on tab 'Arguments'.
I do same with all my projects. What you need to do is :
Create workspace directory on different location than your source code.
Import your source code in your workspace directory. Here don't copy source to your workspace
EDIT
In Eclipse
Go to File->Switch Workspace->Other-> Type "new directory workspace" path, click OK. Eclipse will restart.
Go to File->Import->General-> Existing Projects into Workspace-> Next-> Select Root directory
Eclipse will list your project, select it.
Start editing and saving files.
Thought this does not directly answer your question, as an alternative to using Eclipse IDE for Java files try using Padclipse which is a text editor based on Eclipse.
Padclipse is a light weight text editor based on Eclipse. The basic
product is composed of Eclipse RCP plus Text Editor, Compare and
Search facilities and their dependencies. A few additional third party
plug-ins are included as well.
Check it out here
Also, the default JDK on my system was a 64 bit because of which starting up padclipse failed. Create a padclipse.ini in the folder where you unzipped it in and put in the following contents :
-showsplash
-launcher
padclipse.exe
-name
Padclipse
--launcher.library
plugins\org.eclipse.equinox.launcher.win32.win32.x86_1.0.0.v20070523\eclipse_1017a.dll
-startup
plugins\org.eclipse.equinox.launcher_1.0.0.v20070606.jar
-vm
C:\dev\jdk\1.5\1.5.0_21\jre\bin\server\jvm.dll
Change -vm argument to point to the java.exe or jvm.dll of a 32 bit jdk.
When I export my code as runnable JAR from eclipse all the files that I've set it to grab such as button images and other files are missing even though they are actually in the JAR. I've added getClass().getResource in front of the files but then when I try to run the JAR nothing even happens, any suggestions?
Seems like you not putting your stuff in the right sense. In order to make it work, follow these steps :
Right-Click your Project in Project Explorer Tree.
Go to New -> Source Folder and then provide any Name to the Source Folder.
Now manually add your stuff to this Source Folder so created by you, like if you want to add images then make a New Folder, by manually visiting this Source Folder through File System.
Name this New Folder as images and copy your images to this Folder.
Now go back to your Eclipse IDE and Refresh your Project from the Project Explorer, by Right Clicking your Project, here you be able to see your added content now after refreshing.
Now in order to access, say any image, you will use.
getClass().getResource("/images/yourImageName.extension");
which will return one URL object. Do remember the first forward slash, in this case, since whatever is inside your Source Folder is accessed with the help of this, in simpler terms. Now when you will Run your project, the content of this Source Folder will be automatically added to the bin folder and when you will create a Runnable Jar, then the stuff inside your Source Folder can be accessed as it is.
The path needs to be right for the resource.
For "foo.gif" being at the root of the jar, you must refer to it using "/foo.gif".
If the program works correctly after a complete clean and rebuild, but fails as a jar, you most likely do not have the files included in the jar.
Try to put the folders in the jar the same way that you got them in the program. Put in the same resources in the same places that you have them in the project. The jar will reference to them the same way as in your compiler did.
You need to get the images using stream like this -
this.class.getClassLoader().getResourceAsStream("test.jpg") and make sure the images are present in the jar which you are referencing.
As nIcE cOw said, you just need to create a Source Folder in you Project Explorer Tree.
All the files inside that folder will be in the root project folder.
To refer to them, you must write your projects name slash the file name as it:
getClass().getResource("ProjectName/image.extension");
I hope this helps!