Jump to content

ClassNotFoundException after exporting project


FreakzBoy

Recommended Posts

Hello,

i'm currently working on a mysql database which im trying implement in with my minecraft project.

My problem is, that if i export my project (with the minecraft classes of course) it throws an ClassNotFoundException for "com.mysql.cj.jdbc.Driver"

Strangely, its working in debug mode but not when i export it.

I have also already added the correct mysql-connector.jar to the libraries, as well as searching for reasons online..

I hope that someone will the cause for this and help me out with it.

 

Console output: 

01:47:16	game		info	java.lang.ClassNotFoundException: com.mysql.cj.jdbc.Driver
01:47:16	game		info	at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
01:47:16	game		info	at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
01:47:16	game		info	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
01:47:16	game		info	at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
01:47:16	game		info	at java.lang.Class.forName0(Native Method)
01:47:16	game		info	at java.lang.Class.forName(Class.java:264)
01:47:16	game		info	at me.freakzboy.testclient.TestClient.startClient(CountDown.java:41)
01:47:16	game		info	at net.minecraft.client.Minecraft.startGame(Minecraft.java:575)
01:47:16	game		info	at net.minecraft.client.Minecraft.run(Minecraft.java:410)
01:47:16	game		info	at net.minecraft.client.main.Main.main(Main.java:114)
01:47:16	game		info	jdbc driver unavailable!

 

	public void startClient() {
		
		instance = this;
		
		try {
			
		    Class.forName("com.mysql.cj.jdbc.Driver");
		    
		    //this accesses Driver in jdbc.
		} catch (ClassNotFoundException e) {
		    e.printStackTrace();
		    System.err.println("jdbc driver unavailable!");
		    return;
		}
		MySQL.connect(); 
    	}

 

	public static void connect() {
		
		if(isConnected() == false) {
			try {
				
				con = DriverManager.getConnection("jdbc:mysql://" + host + ":" + port + "/" + database, username, password);
				
				System.out.println("[MySQL] Successfully connected!");
				
			} catch (SQLException e) {
				
				System.out.println("[MySQL] Error.");
				
				e.printStackTrace();
			}
		}
		
	}

 

Thanks,

Freakz

Edited by FreakzBoy
Link to comment
Share on other sites

Minecraft does not ship with this package, you have to shade it into your compiled jar.

Apparently I'm a complete and utter jerk and come to this forum just like to make fun of people, be confrontational, and make your personal life miserable.  If you think this is the case, JUST REPORT ME.  Otherwise you're just going to get reported when you reply to my posts and point it out, because odds are, I was trying to be nice.

 

Exception: If you do not understand Java, I WILL NOT HELP YOU and your thread will get locked.

 

DO NOT PM ME WITH PROBLEMS. No help will be given.

Link to comment
Share on other sites

1 hour ago, diesieben07 said:

Shading is inferior to the jar-in-jar mechanism in Forge.

Good to know. Hadn't heard about this, or if I did, I didn't know it was different.

Apparently I'm a complete and utter jerk and come to this forum just like to make fun of people, be confrontational, and make your personal life miserable.  If you think this is the case, JUST REPORT ME.  Otherwise you're just going to get reported when you reply to my posts and point it out, because odds are, I was trying to be nice.

 

Exception: If you do not understand Java, I WILL NOT HELP YOU and your thread will get locked.

 

DO NOT PM ME WITH PROBLEMS. No help will be given.

Link to comment
Share on other sites

Ok, i tried packaging the mysql-connector-java.jar after i exported my minecraft project and (put the com folder as well as the META-INF folder into my minecraft jar). Unfortunately, its still throwing the ClassNotFoundException: com.mysql.cj.jdbc.Driver and doesnt connect to my mysql database. I did some research on the internet too, and people were talking about dependencies in the META-INF folder and pom.xml which I'm not familiar. Any ideas?

Edited by FreakzBoy
Link to comment
Share on other sites

I forgot to mention that i'm not working on a mod thats going to be added, but on a whole minecraft client that should connect to the database. I basically export my client jar and place the things that are inside it into a normal minecraft jar, thats how i can basically start my client in the launcher. I dont know if you had experience with clients in general yet or only with mods, but it should be close to the same. By the way the link you have posted above, tells me, that i have to put dependency jars into my jar, which i can only get by converting my project into Maven. Is that correct?

Edited by FreakzBoy
Link to comment
Share on other sites

Do not create clients.

This is not negotiable or debatable, thread locked.

This is my Forum Signature, I am currently attempting to transform it into a small guide for fixing easier issues using spoiler blocks to keep things tidy.

 

As the most common issue I feel I should put this outside the main bulk:

The only official source for Forge is https://files.minecraftforge.net, and the only site I trust for getting mods is CurseForge.

If you use any site other than these, please take a look at the StopModReposts project and install their browser extension, I would also advise running a virus scan.

 

For players asking for assistance with Forge please expand the spoiler below and read the appropriate section(s) in its/their entirety.

Spoiler

Logs (Most issues require logs to diagnose):

Spoiler

Please post logs using one of the following sites (Thank you Lumber Wizard for the list):

https://gist.github.com/100MB Requires member (Free)

https://pastebin.com/: 512KB as guest, 10MB as Pro ($$$)

https://hastebin.com/: 400KB

Do NOT use sites like Mediafire, Dropbox, OneDrive, Google Drive, or a site that has a countdown before offering downloads.

 

What to provide:

...for Crashes and Runtime issues:

Minecraft 1.14.4 and newer:

Post debug.log

Older versions:

Please update...

 

...for Installer Issues:

Post your installer log, found in the same place you ran the installer

This log will be called either installer.log or named the same as the installer but with .log on the end

Note for Windows users:

Windows hides file extensions by default so the installer may appear without the .jar extension then when the .log is added the log will appear with the .jar extension

 

Where to get it:

Mojang Launcher: When using the Mojang launcher debug.log is found in .minecraft\logs.

 

Curse/Overwolf: If you are using the Curse Launcher, their configurations break Forge's log settings, fortunately there is an easier workaround than I originally thought, this works even with Curse's installation of the Minecraft launcher as long as it is not launched THROUGH Twitch:

Spoiler
  1. Make sure you have the correct version of Forge installed (some packs are heavily dependent on one specific build of Forge)
  2. Make a launcher profile targeting this version of Forge.
  3. Set the launcher profile's GameDir property to the pack's instance folder (not the instances folder, the folder that has the pack's name on it).
  4. Now launch the pack through that profile and follow the "Mojang Launcher" instructions above.

Video:

Spoiler

 

 

 

or alternately, 

 

Fallback ("No logs are generated"):

If you don't see logs generated in the usual place, provide the launcher_log.txt from .minecraft

 

Server Not Starting:

Spoiler

If your server does not start or a command window appears and immediately goes away, run the jar manually and provide the output.

 

Reporting Illegal/Inappropriate Adfocus Ads:

Spoiler

Get a screenshot of the URL bar or copy/paste the whole URL into a thread on the General Discussion board with a description of the Ad.

Lex will need the Ad ID contained in that URL to report it to Adfocus' support team.

 

Posting your mod as a GitHub Repo:

Spoiler

When you have an issue with your mod the most helpful thing you can do when asking for help is to provide your code to those helping you. The most convenient way to do this is via GitHub or another source control hub.

When setting up a GitHub Repo it might seem easy to just upload everything, however this method has the potential for mistakes that could lead to trouble later on, it is recommended to use a Git client or to get comfortable with the Git command line. The following instructions will use the Git Command Line and as such they assume you already have it installed and that you have created a repository.

 

  1. Open a command prompt (CMD, Powershell, Terminal, etc).
  2. Navigate to the folder you extracted Forge’s MDK to (the one that had all the licenses in).
  3. Run the following commands:
    1. git init
    2. git remote add origin [Your Repository's URL]
      • In the case of GitHub it should look like: https://GitHub.com/[Your Username]/[Repo Name].git
    3. git fetch
    4. git checkout --track origin/master
    5. git stage *
    6. git commit -m "[Your commit message]"
    7. git push
  4. Navigate to GitHub and you should now see most of the files.
    • note that it is intentional that some are not synced with GitHub and this is done with the (hidden) .gitignore file that Forge’s MDK has provided (hence the strictness on which folder git init is run from)
  5. Now you can share your GitHub link with those who you are asking for help.

[Workaround line, please ignore]

 

Link to comment
Share on other sites

Guest
This topic is now closed to further replies.

Announcements



×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.