Could not find or load main class caused by ClassNotFoundException | Together Java | Page 1

sharp osprey Jun 22, 2024, 8:45 PM

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I always get Could not find or load main class caused by ClassNotFoundException why is this despite having a manifest pointing to the main class / entry point I also have jars I have imported in the modules what could be the issue it runs fine in intellij but not in terminal

jolly sorrelBOT Jun 22, 2024, 8:45 PM

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<@&987246399047479336> please have a look, thanks.

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Here is an AI assisted attempt to answer your question 🤖. Maybe it helps! In any case, a human is on the way 👍. To continue talking to the AI, you can use </chatgpt:1108714622413963314>.

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TJ-Bot

I always get Could not find or load main class caused by ClassNotFoundException why is this despite having a manifest pointing to the main class / entry point I also have jars I have imported in the modules what could be the issue it runs fine in intellij

correct main class in my JAR file?

The "Could not find or load main class" error is typically caused by the JVM not being able to locate your main class during runtime. This error is usually due to one of the following reasons:

Incorrect package structure: Make sure that your main class is in the correct package structure defined in the manifest file.
Incorrect classpath: Ensure that the classpath is correctly set in your manifest file or command line arguments.
Missing or incorrect manifest file: Double-check your manifest file to ensure that it correctly specifies the main class and that it is located in the correct directory within your JAR file.
Incorrect main class name: Verify that the fully qualified name of your main class matches exactly what is specified in the manifest file.
JAR file corruption: If none of the above solutions work, try rebuilding your JAR file as it may be corrupted.

To troubleshoot this issue, you can try running your JAR file with a verbose output option (-verbose:class) to see if it provides more information about where the JVM is trying to look for your main class. Additionally, check for any typos or syntax errors in your manifest file and ensure that all necessary dependencies are included in your JAR file.

untold ingot Jun 22, 2024, 11:17 PM

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how are you running the code?

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it sounds likely you are missing a --module-path

sharp osprey Jun 22, 2024, 11:57 PM

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I have the module path also @untold ingot

untold ingot Jun 23, 2024, 12:04 AM

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can you give more info?

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enough to run this situation locally / recreate it?

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the command you are using to launch your code

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etc

sharp osprey Jun 23, 2024, 1:05 AM

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so java -jar file.jar works

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but im trying to run it without java- jar

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file.jar in terminal

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then i get class not found exception

untold ingot Jun 23, 2024, 1:41 AM

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what are the exact commands you mean?

sharp osprey Jun 23, 2024, 1:42 AM

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just cd into the path where the jar lives

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then file.jar in terminal

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I dont want to do the extra java options @untold ingot

hollow dew Jun 23, 2024, 1:55 AM

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sharp osprey I dont want to do the extra java options <@242066553183404032>

if its a jar it has to be with java -jar

untold ingot Jun 23, 2024, 1:56 AM

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can you please just write out the command that works and the one that does not

hollow dew Jun 23, 2024, 1:56 AM

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hollow dew if its a jar it has to be with `java -jar`

You could use a batch script for windows that does that for you

hollow dew Jun 23, 2024, 1:58 AM

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untold ingot can you please just write out the command that works and the one that does not

for what I understand is that java -jar x command is too long to write and "x" command didn't work

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is that or I'm wrong @sharp osprey

untold ingot Jun 23, 2024, 2:00 AM

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if that is the case there is a way to make it work

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but @hollow dew don't call people "too lazy to __"

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it doesn't really foster a good environment

hollow dew Jun 23, 2024, 2:03 AM

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ok

sharp osprey Jun 23, 2024, 3:18 AM

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hollow dew for what I understand is that java -jar x command is too long to write and "x" c...

Yes but it didn’t work doing x

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But it worked for others on my team but they don’t know why and couldn’t show me

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@hollow dew @untold ingot

untold ingot Jun 23, 2024, 3:20 AM

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So the way to make thing.jar work as a command is to prepend a "shebang" line to it

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only works on mac/linux

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but basically if the first bytes of a file are #!java -jar

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it will launch the file with java -jar

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now that makes it unusable with java -jar

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and Nemux is right, it is silly to go this far to avoid writing java -jar

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one way to save run configuration stuff is to put it into a text file

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if you make a file like run.txt

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and put in it

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-jar yourthing.jar

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you can say

hollow dew Jun 23, 2024, 3:22 AM

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untold ingot but basically if the first bytes of a file are `#!java -jar`

On Windows its with a batch file

untold ingot Jun 23, 2024, 3:22 AM

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java @run.txt

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and that works

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which is more amicable to that command growing in whatever way

hollow dew Jun 23, 2024, 3:23 AM

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Or

sharp osprey Jun 23, 2024, 3:23 AM

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Basically my lead developer has made it incumbent that he just runs c:/file/to/jar/thing.jar and run it as a script without making adjustments

hollow dew Jun 23, 2024, 3:23 AM

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better you set a program in your path that runs java -jar

untold ingot Jun 23, 2024, 3:23 AM

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is this a school project?

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and okay if i'm guessing how that can even work

sharp osprey Jun 23, 2024, 3:24 AM

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Nope company work @hollow dew @untold ingot

untold ingot Jun 23, 2024, 3:24 AM

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maybe some old JRE for desktop crap?

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would auto associate .jar with java?

hollow dew Jun 23, 2024, 3:24 AM

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File association I think

sharp osprey Jun 23, 2024, 3:24 AM

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The thing is we are on Java 22

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The latest Java

untold ingot Jun 23, 2024, 3:25 AM

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how are you building your code

sharp osprey Jun 23, 2024, 3:25 AM

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IntelliJ artifacts build with module and dependency look for main class then build the jar

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I urge him just add Java -jar but he doesn’t think it’s a good idea

untold ingot Jun 23, 2024, 3:26 AM

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no offense, but that sounds very amateur. Is your lead dev participating at all?

sharp osprey Jun 23, 2024, 3:26 AM

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He’s not keen on change or growth

untold ingot Jun 23, 2024, 3:26 AM

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what is the thing you are making?

sharp osprey Jun 23, 2024, 3:27 AM

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It’s just a etl desktop app

untold ingot Jun 23, 2024, 3:27 AM

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what are your dependencies

sharp osprey Jun 23, 2024, 3:27 AM

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Delivering data to clients

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MSsql, some gui jars also

untold ingot Jun 23, 2024, 3:27 AM

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and how do you get your app to clients or are you running it on your end

sharp osprey Jun 23, 2024, 3:27 AM

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The app renders data

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And that data goes to file system and is mapped to FileZilla to then ftp data

untold ingot Jun 23, 2024, 3:28 AM

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so its basically a script for you guys

sharp osprey Jun 23, 2024, 3:29 AM

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Yup

untold ingot Jun 23, 2024, 3:29 AM

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that ships stuff over ftp

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(ultimately)

sharp osprey Jun 23, 2024, 3:29 AM

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Yeah

untold ingot Jun 23, 2024, 3:29 AM

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and your lead is the one running it?

sharp osprey Jun 23, 2024, 3:29 AM

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Yeah

untold ingot Jun 23, 2024, 3:30 AM

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Customer is always right on matters of taste, but

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you are on 21 right?

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or err 22

sharp osprey Jun 23, 2024, 3:30 AM

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He’s not a lead per say he’s like a sys / db admin

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22

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The thing is this app is not client facing

untold ingot Jun 23, 2024, 3:30 AM

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are you aware that you do not need to compile your code in 22

sharp osprey Jun 23, 2024, 3:31 AM

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untold ingot are you aware that you do not need to compile your code in 22

Oh how so

untold ingot Jun 23, 2024, 3:31 AM

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java src/Main.java

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instead of a class name you can put a file

sharp osprey Jun 23, 2024, 3:31 AM

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We have code that’s like 8 and below

untold ingot Jun 23, 2024, 3:31 AM

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like a python script

sharp osprey Jun 23, 2024, 3:31 AM

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So we were migrating to Java 22

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But in the process it has all these classpath errors can’t find manifest or main class blah blah

untold ingot Jun 23, 2024, 3:32 AM

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i mean

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you are building it ad-hoc from intellij

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I would expect shit to be broken

sharp osprey Jun 23, 2024, 3:32 AM

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Well it’s getting my lead to understand that he’s not a programmer and how he’s been doing it for years is how it’ll be

hollow dew Jun 23, 2024, 3:33 AM

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sharp osprey But in the process it has all these classpath errors can’t find manifest or main...

I still don't understand why to go this far just to not write java -jar

untold ingot Jun 23, 2024, 3:33 AM

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well lets say for a moment that maybe the "run a jar directly" thing should work out

hollow dew Jun 23, 2024, 3:33 AM

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like you run the program very often

untold ingot Jun 23, 2024, 3:33 AM

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and there is no way to change this guy's opinion

sharp osprey Jun 23, 2024, 3:34 AM

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LUL

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Nope

untold ingot Jun 23, 2024, 3:34 AM

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we have to assume that you are building your jar wrong

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so can you maybe screenshot your folder structure?

sharp osprey Jun 23, 2024, 3:34 AM

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Okay

untold ingot Jun 23, 2024, 3:37 AM

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also which class wasnt found when you ran this stuff before

hollow dew Jun 23, 2024, 3:37 AM

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untold ingot we have to assume that you are building your jar wrong

how so? I think it would say main class is not in manifest rather that class not found

untold ingot Jun 23, 2024, 3:38 AM

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hollow dew how so? I think it would say main class is not in manifest rather that class not...

well he must want to have an uberjar. that would be going wrong

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or rather he needs an uberjar to make his boss's command work

sharp osprey Jun 23, 2024, 3:38 AM

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It weren’t specific

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Those jars I have to add to module libraries

untold ingot Jun 23, 2024, 3:40 AM

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I see an nbproject folder

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maybe it will magically work if you open it in netbeans?

sharp osprey Jun 23, 2024, 3:40 AM

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It works here

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Just not in terminal without Java -jar file.jar

untold ingot Jun 23, 2024, 3:41 AM

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oh

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nononono

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"here" meaning the IDE is meaningless

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tell us the exact error you get

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when it doesn't work

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not part of it

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exactly what it says

sharp osprey Jun 23, 2024, 3:42 AM

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hollow dew Jun 23, 2024, 3:42 AM

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I think when he runs thing.jar in cmd windows try to open it like java thing.jar.class

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and that file doesnt exist

hollow dew Jun 23, 2024, 3:43 AM

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sharp osprey

that doesnt show the error

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tell what error gives running your app in cmd without java -jar

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@sharp osprey

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I know you said class not found but send full error

sharp osprey Jun 23, 2024, 3:46 AM

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hollow dew Jun 23, 2024, 3:47 AM

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sharp osprey

so thats the command that works

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show the one that gives error

sharp osprey Jun 23, 2024, 3:48 AM

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Works like a charm

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But without it

hollow dew Jun 23, 2024, 3:48 AM

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show full error log

hollow dew Jun 23, 2024, 3:48 AM

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sharp osprey But without it

yes

hollow dew Jun 23, 2024, 3:49 AM

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sharp osprey

also r/screenshotsarehard

sharp osprey Jun 23, 2024, 3:51 AM

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could not find or load main class

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when i do prod_feed_v2.jar by itself

hollow dew Jun 23, 2024, 3:51 AM

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sharp osprey could not find or load main class

full error log`

sharp osprey Jun 23, 2024, 3:52 AM

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caused by java.lang.ClassnotFoundException

hollow dew Jun 23, 2024, 3:52 AM

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that's it?

sharp osprey Jun 23, 2024, 3:52 AM

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yup

hollow dew Jun 23, 2024, 3:53 AM

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sharp osprey yup

basically windows tries to run it as java yourapp.jar

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trying to find yourapp.jar.class

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I will try if that happens on my windows

sharp osprey Jun 23, 2024, 3:54 AM

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hollow dew Jun 23, 2024, 3:54 AM

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sharp osprey

send the right part

sharp osprey Jun 23, 2024, 3:55 AM

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the right as as in opposite of left? lol

hollow dew Jun 23, 2024, 3:55 AM

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sharp osprey the right as as in opposite of left? lol

youre not showing full error

sharp osprey Jun 23, 2024, 3:55 AM

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its just fle directories

hollow dew Jun 23, 2024, 3:56 AM

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r/screenshotsarehard 😞

sharp osprey Jun 23, 2024, 3:56 AM

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where my out folder is for the artifacts

hollow dew Jun 23, 2024, 3:56 AM

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well I will try on my pc if its just bad file associatipn by windows

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@sharp osprey yes it is

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does double clicking the jar makes it open with java?

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that is to set file association

sharp osprey Jun 23, 2024, 4:00 AM

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it does a flash thing

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then stops straight away

hollow dew Jun 23, 2024, 4:00 AM

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sharp osprey then stops straight away

your app?

sharp osprey Jun 23, 2024, 4:00 AM

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yeah

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something opens then closes straight away rather

hollow dew Jun 23, 2024, 4:00 AM

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that shouldnt happen

untold ingot Jun 23, 2024, 4:01 AM

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@sharp osprey Use the snipping tool

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to take screenshots

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rather than your phone

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and okay check to see if you have an extra version of java installed

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if its opening with an old java it might crash instantly

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ut also

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WHAT FUCKING CLASS CANT IT FIND

sharp osprey Jun 23, 2024, 4:02 AM

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haha

untold ingot Jun 23, 2024, 4:02 AM

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thats all i want to know

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is it from your stuff or your libraries

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or the jdk

hollow dew Jun 23, 2024, 4:04 AM

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how I can't say the F word too

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lol

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@sharp osprey Send FULL error message

sharp osprey Jun 23, 2024, 4:05 AM

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literally thats it

hollow dew Jun 23, 2024, 4:05 AM

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sharp osprey

No, you didn't take the photo well

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some text isnt shown

untold ingot Jun 23, 2024, 4:06 AM

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the part we need to see is what is to the right of ClassNotFoundException

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https://support.microsoft.com/en-us/windows/use-snipping-tool-to-capture-screenshots-00246869-1843-655f-f220-97299b865f6b

Use Snipping Tool to capture screenshots - Microsoft Support

Learn how to use Snipping Tool to capture a screenshot, or snip, of any object on your screen, and then annotate, save, or share the image.

sharp osprey Jun 23, 2024, 4:07 AM

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hollow dew Jun 23, 2024, 4:08 AM

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sharp osprey

yes just what I said

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it tries to open with java for some reason

sharp osprey Jun 23, 2024, 4:09 AM

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how do you know what part of the picture says this

untold ingot Jun 23, 2024, 4:09 AM

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okay now we are getting somewhere

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hmm

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so for some reason your jar is trying to load a file path as its main class

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do you have winrar or 7zip?

sharp osprey Jun 23, 2024, 4:10 AM

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7zip

untold ingot Jun 23, 2024, 4:10 AM

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can you open the jar file in 7zip

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and look at what is in the Manifest.MF

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if you need to, rename the file to .zip

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...though it should work without that

hollow dew Jun 23, 2024, 4:11 AM

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untold ingot and look at what is in the Manifest.MF

its already working with java -jar so this shouldn't be a problem

sharp osprey Jun 23, 2024, 4:11 AM

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ive got a manifest file

untold ingot Jun 23, 2024, 4:11 AM

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sharp osprey ive got a manifest file

aight, screenshot it

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the contents

sharp osprey Jun 23, 2024, 4:11 AM

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sharp osprey It weren’t specific

that has thi

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this

untold ingot Jun 23, 2024, 4:12 AM

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oh exactly that?

sharp osprey Jun 23, 2024, 4:12 AM

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the 7zip folders or the manifest

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yeah

untold ingot Jun 23, 2024, 4:12 AM

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the manifest you find inside the jar

sharp osprey Jun 23, 2024, 4:12 AM

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yeah

untold ingot Jun 23, 2024, 4:12 AM

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when you look at it in 7zip

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i'm trying to get a handle on what happens when you are running the jar directly

sharp osprey Jun 23, 2024, 4:13 AM

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for some reason i have meta-inf outside of src and one in src

untold ingot Jun 23, 2024, 4:13 AM

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can you try the same thing in PowerShell?

untold ingot Jun 23, 2024, 4:13 AM

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sharp osprey for some reason i have meta-inf outside of src and one in src

oh, thats interesting

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screenshots

sharp osprey Jun 23, 2024, 4:15 AM

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sure

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untold ingot Jun 23, 2024, 4:16 AM

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those files have different sizes

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what is in the one on the left (the one not in src)

sharp osprey Jun 23, 2024, 4:17 AM

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yeah

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that might be because of whitespace

untold ingot Jun 23, 2024, 4:17 AM

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maybe

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okay so if thats not the issue i'm back to being suspicious of your java setup

sharp osprey Jun 23, 2024, 4:18 AM

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should i delete one of them ?

untold ingot Jun 23, 2024, 4:18 AM

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nah its fine

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because being able to run a jar directly without java -jar isn't a normal state of affairs

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its pretty normal for someone to be able to double click a jar

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but running the jar as a file directly...first i've seen it

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is your lead aware that he needs to / would need to be on java 22?

sharp osprey Jun 23, 2024, 4:19 AM

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yeah he has 22 on his machine

untold ingot Jun 23, 2024, 4:19 AM

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does he have a similar issue when running it?

sharp osprey Jun 23, 2024, 4:19 AM

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he hasn't tested it yet

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but my co developer has and it works

untold ingot Jun 23, 2024, 4:20 AM

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have him test it then

sharp osprey Jun 23, 2024, 4:20 AM

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so i think its my set up

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ive reinstalled javase though

untold ingot Jun 23, 2024, 4:20 AM

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then yeah can you go to Add/Remove programs?

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and search for java

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oh what

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no you don't want java se?

sharp osprey Jun 23, 2024, 4:20 AM

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sorry jdk 22

untold ingot Jun 23, 2024, 4:20 AM

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okay well still go to the add/remove programs

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we are gonna see if you have 2 versions of java

hollow dew Jun 23, 2024, 4:22 AM

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sharp osprey sorry jdk 22

uninstall the older version if you have one, and use jarfix tool

sharp osprey Jun 23, 2024, 4:22 AM

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isnt java se developmentt kit just jdk 22

hollow dew Jun 23, 2024, 4:22 AM

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to fix the file association

untold ingot Jun 23, 2024, 4:22 AM

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yeah

sharp osprey Jun 23, 2024, 4:22 AM

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or should i say jdk 22

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okay

untold ingot Jun 23, 2024, 4:22 AM

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but java has gotten a lot of wierd names

sharp osprey Jun 23, 2024, 4:22 AM

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what about jres do i need to change that?

untold ingot Jun 23, 2024, 4:22 AM

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and what happens sometimes is people install a JRE

sharp osprey Jun 23, 2024, 4:22 AM

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or is it embedded

untold ingot Jun 23, 2024, 4:22 AM

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yeah you shouldn't have any

sharp osprey Jun 23, 2024, 4:22 AM

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cool

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ill uninstall then install again

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then also use jarfix?

untold ingot Jun 23, 2024, 4:23 AM

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the "JDK" is just "Java + the compiler and stuff"

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i don't know what jarfix is so i'll leave it to nemux

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also i need to get some sleep

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but we've narrowed down what the issue might be

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thats progress

sharp osprey Jun 23, 2024, 4:23 AM

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from which provider

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thanks @untold ingot

untold ingot Jun 23, 2024, 4:24 AM

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https://adoptium.net/temurin/releases/?version=22

Latest Releases | Adoptium

Eclipse Adoptium provides prebuilt OpenJDK binaries ...

hollow dew Jun 23, 2024, 4:24 AM

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Also check all checkboxes in installer

sharp osprey Jun 23, 2024, 4:24 AM

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oh it worked straight away

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jarfix

hollow dew Jun 23, 2024, 4:25 AM

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sharp osprey oh it worked straight away

wow

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so it is solved?

sharp osprey Jun 23, 2024, 4:26 AM

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yeah

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solved man

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thanks a ton

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okay so we now know

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fileassociations been hijacked

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what is the alternative to jarfix

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would we have to go regedit?

hollow dew Jun 23, 2024, 4:30 AM

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sharp osprey would we have to go regedit?

or install a JDK that solves that issue

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like Azul's one

sharp osprey Jun 23, 2024, 4:35 AM

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i saw an alternative

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HKEY_ etc

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regedit

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Im guessing jarfix does this for you

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but isually making changes on regedit requires you to restart your computer

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but i never did so

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so it may be doing something different

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ah well its solved thanks again @hollow dew

sharp osprey Jun 23, 2024, 5:11 AM

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Thank you @hollow dew

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Thank you @untold ingot

#Could not find or load main class caused by ClassNotFoundException