InvalidModuleDescriptorException when running my first java app

Question

I have started learning Java and encountered a problem when trying to run my first program as given below:

public class HelloWorld {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
     System.out.println("Hello world!");
    }
}

On Eclipse Photon I encounter this error when running it:

 Error occurred during initialization of boot layer
    java.lang.module.FindException: Error reading module: C:\Users\Thomas\eclipse-workspace\HelloWorld\bin
    Caused by: java.lang.module.InvalidModuleDescriptorException: HelloWorld.class found in top-level directory (unnamed package not allowed in module)

I looked and there is my .class file in bin directory and my .java in the src directory.

Is that normal? How do I fix that?

Add the following statement as first line in your code: `package example;`Eclipse will show you an error. Use the _Quick Help_ and choose "Move ..." — LuCio, Jul 02 '18 at 10:14

score 79 · Answer 1 · answered Jun 23 '19 at 13:23

79

I was getting the same error. Deleting the module-info.java file solved it for me.

answered Jun 23 '19 at 13:23

Jaideep Dhumal

903
6
6

1

This fixed my problem too. – James Reid Aug 04 '19 at 02:39
Glad I could help :) – Jaideep Dhumal Oct 09 '19 at 08:32
1

nice solution! Thank you, – 서영재 Sep 24 '20 at 08:39
Glad I could help :) – Jaideep Dhumal Oct 12 '20 at 15:14
2

This answer should get green tick. Thank you – Shubham K. Jun 12 '21 at 06:06
5

Although this answer "solve" the error. A better solution is to [properly setup the module system](https://openjdk.java.net/projects/jigsaw/quick-start) after jdk 9. – samabcde Sep 25 '21 at 15:09
4

This answer is not useful. It only works by coincidence. Depending on the environment, deleting module-info.java introduces other problems, especially when using components from the JDK that now require modules to be setup properly (like module `java.smartcardio`). Instead, properly setup the module system as pointed out by @samabcde. – Christian Hujer Sep 22 '22 at 05:00

score 26 · Answer 2 · edited Sep 01 '20 at 15:53

26

It seems that you haven't created a package. My usual procedure in Eclipse is:

Create a new Java project
Inside that project: Create a new package
Inside that package: Create a new Java class

Eclipse will help you a lot with the settings. Then just copy your code into that class and hit the 'start' button.

edited Sep 01 '20 at 15:53

Naman

27,789
26
218
353

answered Jul 02 '18 at 10:13

Sven Affeld

311
3
8

score 6 · Answer 3 · answered Sep 24 '18 at 16:42

6

by removing module class problem solved for me in eclipse

answered Sep 24 '18 at 16:42

Naveen Neelam

69
1
2

4

Please add more details to your answer. – Ashu Sep 24 '18 at 17:08
Worked for me too ```module-info.class``` in my case was located at ```build/classes/``` in my case. – dennohpeter Apr 10 '20 at 11:28

score 0 · Answer 4 · answered May 17 '19 at 08:23

i moved my main class and sample.fxml file to a new package that throws this error below

"Error occurred during initialization of boot layer java.lang.module.FindException: Error reading module: C:\Users\Thomas\eclipse-workspace\HelloWorld\bin Caused by: java.lang.module.InvalidModuleDescriptorException: HelloWorld.class found in top-level directory (unnamed package not allowed in module)"

i moved my class file and fxml file to normal position. it fix my problem. but i have to find why it happends. cheers....

score 0 · Answer 5 · answered Jun 05 '21 at 12:10

0

Executing the project from another workspace solved for me in Eclipse.

answered Jun 05 '21 at 12:10

Lucas Favaro Borsatto

114
1
3
11

Nabeel Bhatti · Answer 6 · 2022-02-10T05:05:04.850

0

create a package and refactor your Main class in that package in your case its HelloWorld then it will run fine. To understand how modules work in java please watch this spectacular video MODULES IN JAVA

edited Feb 10 '22 at 05:05

answered Feb 09 '22 at 11:24

Nabeel Bhatti

99
2
10

2

Your answer could be improved with additional supporting information. Please [edit] to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers [in the help center](/help/how-to-answer). – Community Feb 09 '22 at 11:30

score 0 · Answer 7 · edited Apr 03 '23 at 13:37

0

I've solved it according to these steps:

right click on your main project name
choose the new package and fill in the name
choose (radio button) "create package info"
click ok
finally, in the package explorer, drag your class under the new package which you created

edited Apr 03 '23 at 13:37

Arman

126
3
14

answered Jan 02 '23 at 09:48

NIMA

21
1
1
3

3

Using bullet points would make your answer easier to follow. Ex: - Step 1 - Step 2 - ... – tinsukE Jan 02 '23 at 14:54

score 0 · Answer 8 · answered Feb 12 '23 at 02:31

0

Delete module-info.java from your project and run ,it should work. Or Create package and then create class inside package.

answered Feb 12 '23 at 02:31

Ashish Gupta

105
1
5

InvalidModuleDescriptorException when running my first java app

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