I'm trying to comprehend how creating executable jars and file paths work, so please bear with me.
I have a small program, which is supposed to upload some Firmware to Servers. These Firmwares have a combined size of about 650MB. All in all, the Project Folder takes up about 2.2GB of space.
In the program itself, I have some Strings that refer to the name of the folder that contains the firmware.
"src\\com\\java\\myProgram\\data\\bios_fw\\"+biosFWPath+"\\"+biosFW
When testing in the IDE, this works without problem.
So here's my question(s): Will this still work if I build the program as executable jar? I have already noticed that the jar I created holds only about 450MB. Does it even contain the firmware then? And if it does, will the program be able to find the path specified?
Furthermore, what would be the proper way of "installing" these folders together with the jar on a Users PC?
Thanks!
As a .jar file is a java archive file, you can open it and look yourself as we don't know how you build your .jar.
But considering the future, I would remove the absolute path and use a relative path to a directory where you can insert the firmware in case the fw got updated, so you don't have to build your program each time.
The proper way, when you want to keep the FW in your project is using ClassLoader.
I wanted to upload some .java files on github, I don't remember if I uploaded the right files. I have been told that the files I should've submitted were missing. I checked the last commit, and the files I should've submitted were marked with "BIN" and were of type "classname".class instead of "classname".java, underneath each one of them it says "Binary file not shown" instead of the code. I would like to know what happened so that I can avoid this in the future. I have never experienced this before on github. What did I upload? I don't think I had any .class files regarding this project.
From what you say seems like you added files to your commit that shouldn't be added.
Well, to fix this, just remove those files, commit and push the changes. Done.
To avoid this scenario in the future and not only for you but for your team, you can create a .gitignore file at the root of the repository. This file contains patterns of paths (files and folders) so git will ignore those files when showing the state of the branch. If there's no such .gitignore file then create one and add the following:
*.class
bin/
Also, you can add more entries in this file to support omitting other files generated by IDE, for example. There are curated lists you can find like https://gist.github.com/chhh/4961200 or https://www.gitignore.io/api/eclipse
/bin is usually a folder that contains binary files or compiled stuff in general. You should never put it in a repo.
It's not dangerous, but it wastes space and it's something that has to be compiled in each one's computer anyway, so it's pointless to put them in the repo :)
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.
By typing jar -tf myJar.jar MyProject I get in the file list, besides the normal .java and .class files, also a .java~ file.
I have read googling it around that it is due to some other incomplete version of the file.java. If so, How can I go ahead and remove those files? since in the real folder there are no other files than file.java and file.class.
Thanks in advance.
They're almost certainly just backup files automatically created by whatever text editor you're using. You should be fine to remove them.
I'm sure they are in the real folder - it's possible your shell/explorer is hiding them from you. Just try using a command line to remove them by name, even if they don't show up on autocomplete.
(It's hard to be more specific when we don't know which editor you're using, which operating system, or how you're looking at the directory...)
Those are vim backup files. See here and here for some configuration options to avoid cluttering up your working directories.
I would like to modify a file inside my jar. Is it possible to do this without extracting and re jarring, from within my application?
File i want to modify are configuration files, mostly xml based.
The reason i am interested in not un jarring is that the application is wrapped with launch4j if i unjar it i can't create the .exe file again.
You can use the u option for jar
From the Java Tutorials:
jar uf jar-file input-file(s)
"Any files already in the archive having the same pathname as a file being added will be overwritten."
See Updating a JAR File.
Much better than making the whole jar all over again. Invoking this from within your program sounds possible too. Try Running Command Line in Java
You can use Vim:
vim my.jar
Vim is able to edit compressed text files, given you have unzip in your environment.
Java jar files are the same format as zip files - so if you have a zip file utility that would let you modify an archive, you have your foot in the door. Second problem is, if you want to recompile a class or something, you probably will just have to re-build the jar; but a text file or something (xml, for instance) should be easily enough modified.
As many have said, you can't change a file in a JAR without recanning the JAR. It's even worse with Launch4J, you have to rebuild the EXE once you change the JAR. So don't go this route.
It's generally bad idea to put configuration files in the JAR. Here is my suggestion. Search for your configuration file in some pre-determined locations (like home directory, \Program Files\ etc). If you find a configuration file, use it. Otherwise, use the one in the JAR as fallback. If you do this, you just need to write the configuration file in the pre-determined location and the program will pick it up.
Another benefit of this approach is that the modified configuration file doesn't get overwritten if you upgrade your software.
Not sure if this help, but you can edit without extracting:
Open the jar file from vi editor
Select the file you want to edit from the list
Press enter to open the file do the changers and save it
pretty simple
Check the blog post for more details
http://vinurip.blogspot.com/2015/04/how-to-edit-contents-of-jar-file-on-mac.html
I have similar issue where I need to modify/update a xml file inside a jar file.
The jar file is created by a Spring-boot application and the location of the file is BOOT-INF/classes/properties
I was referring this document and trying to replace/update the file with this command:
jar uf myapp.jar BOOT-INF/classes/properties/test.xml
But with this, it wont change the file at the given location. I tried all the options also but wont work.
Note: The command I am executing from the location where jar file is present.
The solution I found is:
From the current location of jar file, I created folders BOOT-INF/classes/properties
Copy the test.xml file into the location BOOT-INF/classes/properties.
Run the same command again. jar uf myapp.jar BOOT-INF/classes/properties/test.xml
The xml file has been changed in the jar file.
Basically you need to create a folder structure like where the file is located into the jar file. Copy the file at that location and then execute the command.
The problem with the documentation is that, it does not have enough examples as well as explanation around common scenarios.
This may be more work than you're looking to deal with in the short term, but I suspect in the long term it would be very beneficial for you to look into using Ant (or Maven, or even Bazel) instead of building jar's manually. That way you can just click on the ant file (if you use Eclipse) and rebuild the jar.
Alternatively, you may want to actually not have these config files in the jar at all - if you're expecting to need to replace these files regularly, or if it's supposed to be distributed to multiple parties, the config file should not be part of the jar at all.
To expand on what dfa said, the reason is because the jar file is set up like a zip file. If you want to modify the file, you must read out all of the entries, modify the one you want to change, and then write the entries back into the jar file. I have had to do this before, and that was the only way I could find to do it.
EDIT
Note that this is using the internal to Java jar file editors, which are file streams. I am sure there is a way to do it, you could read the entire jar into memory, modify everything, then write back out to a file stream. That is what I believe utilities like 7-Zip and others are doing, as I believe the ToC of a zip header has to be defined at write time. However, I could be wrong.
Yes you can, using SQLite you can read from or write to a database from within the jar file, so that you won't have to extract and then re jar it, follow my post http://shoaibinamdar.in/blog/?p=313
using the syntax "jdbc:sqlite::resource:" you would be able to read and write to a database from within the jar file
Check out TrueZip.
It does exactly what you want (to edit files inline inside a jar file), through a virtual file system API. It also supports nested archives (jar inside a jar) as well.
Extract jar file for ex. with winrar and use CAVAJ:
Cavaj Java Decompiler is a graphical freeware utility that reconstructs Java source code from CLASS files.
here is video tutorial if you need:
https://www.youtube.com/watch?v=ByLUeem7680
The simplest way I've found to do this in Windows is with WinRAR:
Right-click on the file and choose "Open with WinRAR" from the context menu.
Navigate to the file to be edited and double-click on it to open it in the default editor.
After making the changes, save and exit the editor.
A dialogue will then appear asking if you wish to update the file in the archive - choose "Yes" and the JAR will be updated.
most of the answers above saying you can't do it for class file.
Even if you want to update class file you can do that also.
All you need to do is that drag and drop the class file from your workspace in the jar.
In case you want to verify your changes in class file , you can do it using a decompiler like jd-gui.
As long as this file isn't .class, i.e. resource file or manifest file - you can.