Eclipse Error: Could not find or load main class

Question

Have Googled extensively on this error, but I can't seem to fix the problem. I've written a basic java program in Eclipse Juno, as follows:

public class HelloWorld {

    /**
     * @param args
     */

    public static void main(String[] args) {
        System.out.println("Hello Eclipse!");
    }

}

After clicking Run, I get: "Error: Could not find or load main class HelloWorld". This error message applies to all my other projects in the same workspace. I've tried switching workspaces but the error still appears.

I'm on Windows 7 64-bit. Any help would be appreciated!

Have you tryed to select the project and then go to Run -> Run As menu? there you can chose the project type and the main class — Joan, May 02 '13 at 09:35
7+ different answers, all of which the submitters claimed worked suggests that this question is "too broad" — Raedwald, Jan 27 '14 at 12:51
7+ different answers, all of which the submitters claimed worked suggests that eclipse is a piece of cr*p that gives the same idiotic error message for 7+ different errors. — J. Ed, Apr 27 '14 at 10:24
Raedwald, do you even forums? How could I have made my question any more specific? The fact that it's received more than 25,000 views is an indication that many people suffer from this problem. sJhonny -- totally agree with ya mate. Eclipse turns me off from programming in Java. Oh, and by the way, if anyone's wondering: exactly a year on since I posted this question... I still haven't solved the problem. lel — Fezzo, May 03 '14 at 12:18
In my case, when the project had build path issue, this happened. — whoami, Apr 10 '15 at 01:32
http://stackoverflow.com/questions/11235827/eclipse-error-could-not-find-or-load-main-class/31711547#31711547 — Alisa, Jul 29 '15 at 21:35
Project -> Clean will remove any existing class files and completely rebuild the project. There's more information on Eclipse's clean function — Girdhar Singh Rathore, Oct 07 '16 at 15:49
right clicked in my project folder ->build path->use as source worked for me — Aayush Neupane, May 21 '20 at 02:27
In my case, my lib path missing a jar. that is why it did not compile — Feng Zhang, Jan 19 '21 at 00:18

score 110 · Answer 1 · edited May 23 '17 at 11:47

110

This just happened to me today after updating my JRE. I cleaned the project and it started working again.

Project -> Clean will remove any existing class files and completely rebuild the project. There's more information on Eclipse's clean function here.

edited May 23 '17 at 11:47

Community

1
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answered Jan 16 '14 at 19:15

Nathan

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3

This worked perfectly for me. I had a problem where Eclipse threw that error because I had manually deleted some *.class files. I like this solution much better than fiddling around with this or that configuration option. Simply use **Project -> Clean...** and voilà! – Malte Skoruppa Apr 02 '14 at 12:45
2

I started my very first Java project, and got this error. I guess it allows you to run without ever building. Ah, Eclipse, why you gotta be that way? This worked, thank you. – TheGerm Dec 09 '14 at 21:38
1

Worked perfectly. Thanks. – Terry Carter Feb 10 '17 at 20:49
1

This is worked for me. Thanks. – Thusitha Indunil Oct 07 '19 at 10:49
Oh!! Thanks a ton! Worked for me as well – Alisha Raju Apr 15 '21 at 09:49

score 98 · Answer 2 · edited Dec 26 '22 at 07:58

98

I just ran into that problem. The cause... not sure. It only happened to me after I added a new JVM. My solution:

went to run configurations: - run->run configurations

In the Classpath tab:

Select Advanced
Add where Eclipse usually put the *.class for the projects, which is in bin. So I added the bin directory for the project.

edited Dec 26 '22 at 07:58

starball

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answered Jun 28 '13 at 01:47

myluco

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@tbeernot I think that what you said can also be an issue, I had a similar problem where my maven project wouldn't update properly so I tried to defer from using maven by just removing the maven libraries and the pom.xml all together and just referencing the libraries locally, after doing so the project stopped running the main classes. I recreated the project without the maven configuration and the classes ran fine afterwards. If you have a pom file configure as a maven project, if you have a maven project, ensure that you have the proper maven configuration – Mar 29 '15 at 15:32
3

Add what? ('Add where Eclipse usually put the *.class for the projects, which is in bin. So I added the bin directory for the project.') There are several options.. – Joe Aug 16 '17 at 04:37

score 44 · Answer 3 · answered Sep 10 '13 at 18:52

44

I deleted a jar file from the bin directory. Right click on your project - Properties then Libraries tab. There was a red flag in there. I removed the jar file from the Libraries and it worked.

answered Sep 10 '13 at 18:52

lake

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After days or searching, this enlighting answer was found. Thanks a zillion times over :) – JavaDeveloper Nov 02 '15 at 21:03
1

@lake it worked for me,can you please explain how a unused jar leads to this kind of problem – Narendra Jaggi Dec 30 '15 at 18:49
1

Works for me!!!! Awesome! – xxx222 Apr 05 '16 at 04:51
1

Wish I could give you more credits. saved me a lot of time – Ankur Bhatia May 13 '16 at 15:03
1

I added proper jar files and this error is gone. – gauti Sep 07 '17 at 11:00
Simply amazing. – Tahlor Oct 29 '17 at 08:48
Thanks a lot...This worked for me. – Sonal Dalal Feb 15 '18 at 13:16

score 22 · Answer 4 · answered May 02 '13 at 09:37

22

It seems that the class is not compiled by Eclipse.

Few pointers could be-

Check if the .class file exists in your output folder.To know your output folder Right Click on Project->Properties->Java Build Path(Check at bottom).
Check if Project->build Automatically is checked in the menu.
Check if the HelloWorld class is in src folder or not.Right Click on Project->Properties->Java Build Path(Check source tab).

answered May 02 '13 at 09:37

Jaydeep Rajput

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Regarding your pointers - 1. The .class file does not exist directly in my output folder - it's located in a subfolder called bin. 2. Yes, it is checked. 3. In my src folder, I can only see HelloWorld.java and no .class file. My class is in the (default package), if that helps at all. – Fezzo May 02 '13 at 11:28
Seems this helped: `Project->build Automatically` – mrgloom Jul 03 '17 at 09:10

score 14 · Answer 5 · edited Jun 10 '18 at 18:25

14

Same Problem occur with me.I went to Project > Properties > Java BuildPath.

There In order of export , I moved up my java/main to the top priority.

edited Jun 10 '18 at 18:25

Hemant Patel

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answered Sep 13 '13 at 10:24

Shashank Awasthi

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score 4 · Answer 6 · answered Sep 03 '13 at 00:47

4

that's because you guys created the class one time with the main method & after that may be you have been deleted that form or workplace & still some of the files exist ,i will suggest you to create that form or workspace again & then delete it by clicking on it completely,then after that if you created the some class like Runner class try to run it again.

answered Sep 03 '13 at 00:47

Ahuramazda

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Deleting all Eclipse created files and the workspace seems to have worked for me. – EM-Creations Jan 04 '16 at 16:11
this was my problem - using the scala ide – Steve Harville Mar 21 '19 at 13:34

score 2 · Answer 7 · edited Oct 19 '13 at 08:38

2

This happened to me. I noticed that someone said I have to create an entire new WORKSHOP! Why? Because I installed a newer JRE version and that won't allow other previous versions to run on it. So all those old files I have become useless in a way. Not really, Just copy and paste it to new class and change it to an unused class name.

edited Oct 19 '13 at 08:38

Qantas 94 Heavy

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answered Jun 01 '13 at 02:52

Akeme Ubom

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This is the only solution that has worked for me. Thank you, @Akeme – Shahar May 10 '19 at 14:37

score -8 · Answer 8 · answered Sep 07 '13 at 03:04

-8

if your package name is same with your class name this problem will occur.

answered Sep 07 '13 at 03:04

user2756160

17

Eclipse Error: Could not find or load main class

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