Eclipse Error: Could not find or load main class [duplicate]

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!

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
– J. Ed, Commented Apr 27, 2014 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
– Fezzo, Commented May 3, 2014 at 12:18
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
– Girdhar Singh Rathore, Commented Oct 7, 2016 at 15:49

Community · Accepted Answer · 2017-05-23 11:47:12Z

111

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, 2017 at 11:47

CommunityBot

11 silver badge

answered Jan 16, 2014 at 19:15

Nathan

2,1033 gold badges21 silver badges33 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Malte Skoruppa Over a year ago

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!

TheGerm Over a year ago

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.

starball · Accepted Answer · 2022-12-26 07:58:21Z

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, 2022 at 7:58

starball♦

59.6k53 gold badges316 silver badges1k bronze badges

answered Jun 28, 2013 at 1:47

myluco

1,0976 silver badges4 bronze badges

2 Comments

user2707813 Over a year ago

@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

Joe Over a year ago

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..

lake · Accepted Answer · 2013-09-10 18:52:52Z

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, 2013 at 18:52

lake

4594 silver badges2 bronze badges

6 Comments

JavaDeveloper Over a year ago

After days or searching, this enlighting answer was found. Thanks a zillion times over :)

Narendra Jaggi Over a year ago

@lake it worked for me,can you please explain how a unused jar leads to this kind of problem

xxx222 Over a year ago

Works for me!!!! Awesome!

Ankur Bhatia Over a year ago

Wish I could give you more credits. saved me a lot of time

gauti Over a year ago

I added proper jar files and this error is gone.

|

Jaydeep Rajput · Accepted Answer · 2013-05-02 09:37:20Z

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 2, 2013 at 9:37

Jaydeep Rajput

3,70320 silver badges35 bronze badges

2 Comments

Fezzo Over a year ago

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.

mrgloom Over a year ago

Seems this helped: Project->build Automatically

Hemant Patel · Accepted Answer · 2018-06-10 18:25:13Z

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, 2018 at 18:25

Hemant Patel

3,2801 gold badge24 silver badges32 bronze badges

answered Sep 13, 2013 at 10:24

Shashank Awasthi

3471 gold badge4 silver badges10 bronze badges

Comments

Ahuramazda · Accepted Answer · 2013-09-03 00:47:49Z

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 3, 2013 at 0:47

Ahuramazda

4379 silver badges14 bronze badges

2 Comments

EM-Creations Over a year ago

Deleting all Eclipse created files and the workspace seems to have worked for me.

Steve Harville Over a year ago

this was my problem - using the scala ide

Qantas 94 Heavy · Accepted Answer · 2013-10-19 08:38:06Z

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, 2013 at 8:38

Qantas 94 Heavy

16k31 gold badges74 silver badges89 bronze badges

answered Jun 1, 2013 at 2:52

Akeme Ubom

311 bronze badge

1 Comment

Shahar Over a year ago

This is the only solution that has worked for me. Thank you, @Akeme

user2756160 · Accepted Answer · 2013-09-07 03:04:12Z

-8

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

answered Sep 7, 2013 at 3:04

user2756160

17

Collectives™ on Stack Overflow

Eclipse Error: Could not find or load main class [duplicate]

8 Answers 8

2 Comments

2 Comments

6 Comments

2 Comments

Comments

2 Comments

1 Comment

Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

8 Answers 8

2 Comments

2 Comments

6 Comments

2 Comments

Comments

2 Comments

1 Comment

Comments

Linked

Related