Error: Selection does not contain a main type

Question

I am trying to run some java files in a new project. So I make the project, put the files in it and I try to run the main file so my game starts.

I get an error that says selection does not contain a main type.

I have tried several ways to run it:

Some say to launch eclipse again, tried this a dozen times.
Somewhere else someone pointed to open a new project and make a build path to the old project.

Didn't work either.

I am pretty sure it must work because I ran it a few hours ago at school. How do I get this working? Thank you in advance!

Do you have a `public static void main(String[] args)` anywhere? — , Apr 25 '13 at 21:40
i dont know what causes this, or how to solve it, but it sure has happened to me with public classes that do have a main method (correctly declared of course). Just wanted to point out that it may not be as simple as you might think — jambriz, Apr 25 '13 at 21:54
I think all the probes point that he's trying to run some classes without a main method. We'll continue investigating. — aran, Apr 25 '13 at 21:55
Maybe it is a maven project so click in the name of your project and hit the follow keys alt+f5 to update the project. — André Luís Tomaz Dionisio, Jan 05 '18 at 16:36
Ten years later, and I receive it on version 2022-06 of eclipse. Running on Linux Ubuntu 22.04. Was there ever a viable answer among the many given? Looks like a lot of shot-iin-the-dark responses. — TheGeeko61, Jul 12 '22 at 00:57

score 93 · Answer 1 · edited Feb 15 '22 at 13:45

93

Right click on the folder where you put your main class then click on Build Path --> Use as Source Folder.

Finally run your main file as java application. Hope this problem will be solved.

If the option 'Use as Source Folder' is not visible then inside the 'Build Path' select the option 'Remove from Build Path'. This will allow 'Use as Source Folder' option to appear in the 'Build Path'.

edited Feb 15 '22 at 13:45

Community

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answered Apr 11 '14 at 23:41

Rashid

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this worked for me. I had the source code for Java Fundamentals from Deital...ti has chapters has folders and java code inside it. I moved all of them within source but still I need to do this step to make it work. – Ashu Sep 06 '18 at 02:12
The Source Folder and target folder (where **Eclipse** puts your main class) are different things. You mean "Where you put the source file for main class". – Gangnus Apr 24 '19 at 05:06
This helped me solve the problem when i had installed eclipse and was running the program for the first time – Devrath Jul 28 '19 at 06:58
That changed the package of all class files to be "default package".. – nsandersen Jan 12 '21 at 11:31

score 48 · Answer 2 · answered Sep 20 '13 at 02:11

48

The other answers are all valid, however, if you are still having a problem you might not have your class inside the src folder in which case Eclipse may not see it as part of the project. This would also invoke the same error message you have seen.

answered Sep 20 '13 at 02:11

zen

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Thanks, the files not being in the src folder was the problem for me. – Dois Feb 01 '15 at 06:14

score 28 · Accepted Answer · edited Feb 18 '21 at 15:36

28

I hope you are trying to run the main class in this way, see screenshot:
screenshot of Eclipse file context menu

If not, then try this way. If yes, then please make sure that your class you are trying to run has a main method, that is, the same method definition as below:

public static void main(String[] args) {
    // some code here
}

I hope this will help you.

edited Feb 18 '21 at 15:36

MC Emperor

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answered Apr 26 '13 at 06:47

NoNaMe

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mishal153 · Answer 4 · 2014-04-22T18:54:47.513

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I resolved this by adding a new source folder and putting my java file inside that folder. "source folder" is not just any folder i believe. its some special folder type for java/eclipse and can be added in eclipse by right-click on project -> properties -> Java buld path -> Source and add a folder

edited Apr 22 '14 at 18:54

answered Apr 22 '14 at 18:44

mishal153

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I added the java project to its own source path and then got another error (Could not find or load main class com...), but at least it moved on a bit :) . Hard to believe how poor Eclipse is on this point. – nsandersen Mar 30 '21 at 07:59
This solution worked. – Vishwajeet Singh Aug 27 '23 at 04:55

score 5 · Answer 5 · answered Apr 25 '13 at 22:02

5

The entry point for Java programs is the method:

public static void main(String[] args) {
    //Code
}

If you do not have this, your program will not run.

answered Apr 25 '13 at 22:02

score 3 · Answer 6 · answered Mar 06 '14 at 15:15

Few things to check out:

Do you have a main package? do all of your classes are under this package?
Do you use a main class with public static void main(String[] args)?
Do you declare: package ; in your main class?
You can always clean the project before running it. In Eclipse - Just go to Project -> clean then run the app again.

score 3 · Answer 7 · answered Sep 01 '14 at 17:30

3

I ran into the same problem. I fixed by right click on the package -> properties -> Java Build Path -> Add folder (select the folder your code reside in).

answered Sep 01 '14 at 17:30

Yang Zhang

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Unless this is on a different version, `package` should be `project` in your above path. – Carcigenicate Feb 03 '15 at 01:54

score 3 · Answer 8 · answered Dec 30 '15 at 18:47

3

I am running eclipse from Ubuntu. Had this same problem and was able run the program through terminal. So I just moved the existing public static void main(String[] args) { just below the class declaration (it got automatically formatted by eclipse) and the next launch was successful. Then moved the main method back to where it was before and it worked fine this time.

answered Dec 30 '15 at 18:47

hipokito

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This answer neatly points to some Eclipse bug and successfully works it around. Seemingly nonsense action mentioned in the answer worked for me even if cleaning the project did not work and all the other things were all right. It looks that Eclipse sometimes holds some invalid class state even after cleaning the project and it initiates the refresh only after the Java file is edited and saved. Context: I copied some Java files over existing ones and then the issue started. – miroxlav Nov 07 '18 at 21:05

score 3 · Answer 9 · answered Jun 01 '19 at 19:06

I had this problem in two projects. Maven and command line worked as expected for both. The problems were Eclipse specific. Two different solutions: Project 1): Move the main method declaration to the top within the class, above all other declarations like fields and constructors. Crazy, but it worked. Project 2): The solution for Project 1) did not remedy the problem. However, removing lombok imports and explicitly writing a getter method solved the problem

Conclusion: Eclipse and/or the lombok plugin have/has a bug.

I had the same problem with an AWS SDK package import. I had to remove `import com.amazonaws.regions.Regions;` from the main class to be able to run the app from Eclipse. I'm using AWS Java SDK v. 1.11.729. — gparis, Feb 26 '20 at 11:17

score 3 · Answer 10 · answered Mar 20 '21 at 04:59

Looks too late to answer but might help someone,

Having same problem i solved it by following steps:::::

Select Main class in eclipse then click on Window in menu bar,

Window-->Show view-->Select Outline

Right click on main(String[]):void then Run As --> java Application

By doing this you can run the main method directly. This worked for me

score 2 · Answer 11 · answered Mar 04 '19 at 05:32

Right Click > Run AS > Run Configurations

In this screen if your "Main class" Text field is empty, then add the class name by clicking "Search" button on the right side of the text field and choose the class file. And then click "Run" button on the bottom of the configuration screen. That's it

score 1 · Answer 12 · answered Feb 28 '14 at 16:47

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You must place all your files (file.java) under the root folder SRC.

answered Feb 28 '14 at 16:47

Dev M

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score 1 · Answer 13 · answered Sep 21 '18 at 07:05

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Make sure the main in public static void main(String[] args) is lower case. For me it didn't work when I had it with capital letter.

answered Sep 21 '18 at 07:05

sander

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score 1 · Answer 14 · edited May 15 '19 at 06:50

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Put your Main Java class file in src/main/java folder and check if there is not any error in 'Java Build Path' by following right click on project and select Java Build Path->Source.

edited May 15 '19 at 06:50

Lalji Dhameliya

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answered May 15 '19 at 05:41

Rajiv Ranjan

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score 1 · Answer 15 · answered Aug 14 '19 at 05:03

If you are working with a Maven project you have to understand the fact that directory layout is bit different. In this the package name must be src/main/java.

For this update your source folder by right click on project root folder -> properties -> java build path -> source tab. Here remove all other source folders as they might have been added in wrong manner. Now, select project /src/main/java as the source folder. Add and apply the changes. Now refresh your workspace using F5.

This should fix the issue of not recognizing a main type.

S14321K · Answer 16 · 2023-06-01T06:11:33.697

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---> Right click on the projecct and select properties.
---> Select Java Build Path

---> Select Source tab, see source folders on build path is pointing to your project/src path. If not, select Add folder and select the src folder.

---> Under Default output folder see that it is pointing to your ProjectName/src

Solution - 2

Or Try this way - https://stackoverflow.com/a/76375396/11962586

edited Jun 01 '23 at 06:11

answered Mar 04 '23 at 18:55

S14321K

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score 0 · Answer 17 · answered Apr 30 '14 at 06:50

I ran into the same issue and found that there was an extra pair of braces (curly brackets) enclosing public static void main(String args) { ... }. This method should really be at the top scope in the class and should not be enclosed around braces. It seems that it is possible to end up with braces around this method when working in Eclipse. This could be just one way you can see this issue when working with Eclipse. Happy coding!

score 0 · Answer 18 · answered May 26 '14 at 05:42

I had this happen repeatedly after adding images to a project in Eclipse and making them part of the build path. The solution was to right-click on the class containing the main method, and then choose Run As -> Java Application. It seems that when you add a file to the build path, Eclipse automatically assumes that file is where the main method is. By going through the Run As menu instead of just clicking the green Run As button, it allows you to specify the correct entry-point.

What if it says this although there *is* a main method? – trusktr Jul 12 '14 at 00:02 — trusktr, Jul 12 '14 at 00:02

score 0 · Answer 19 · answered Sep 08 '14 at 13:07

0

When you save your file, make sure it has the extension .java. If it does not, Eclipse won't know to read it as a java file.

answered Sep 08 '14 at 13:07

KC McLaughlin

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likejudo · Answer 20 · 2020-06-29T19:28:24.133

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I had this issue because the tutorial code I was trying to run wasn't in the correct package even though I had typed in the package name at the top of each class.

I right-clicked each class, Refactor and Move To and accepted the package name suggestion.

Then as usual, Run As... Java Application.

And it worked :)

edited Jun 29 '20 at 19:28

answered Jun 29 '20 at 19:21

likejudo

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score 0 · Answer 21 · answered Mar 02 '21 at 16:26

0

You must check this as well, Go to Java build path -> config build path, check that JRE System Library [Java SE -version] is check marked, try running the code again. This fixed my issue.

answered Mar 02 '21 at 16:26

Anshul Khatri

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score 0 · Answer 22 · answered Oct 18 '21 at 18:51

In my case I was using ant to perform the build, and clearly had the class setup in the build.xml file:

<target name="jar">
  <jar destfile="ec-stats.jar" includes="bin/**,src/**">
    <manifest>
        <attribute name="Main-Class" value="my.package.MyStatistics" />
    </manifest>
  </jar>
</target>

But it still kept giving me the same error, until I right-clicked on the folder in Eclipse and chose Build Path -> Use As Source Folder.

See also Error: Selection does not contain a main type

score 0 · Answer 23 · answered Oct 20 '21 at 17:58

Solved the issue as following:

Going in Properties of the Project

1.1) Inside "Java Compiler": chose the: "Compiler compliance level:" to a specific version of JDK (in my case I choosed 15)
1.2) Inside "Java Build Path", in the tab "Libraries", at the Modulepath: change the "JRE System Library" to the same of the version you choosed at step 1.1 above (in my case I picked JDK 15)

Run the java file that contains a main method

score 0 · Answer 24 · answered Mar 26 '22 at 15:19

0

This can be resolved in two steps if you are using Eclipse IDE.

Step I: Right click on the project and click Maven > Choose Up-date Project

Step II: Select the project the click Ok button

Hope this helps.✔

answered Mar 26 '22 at 15:19

Syed Aaqib Hussain

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score 0 · Answer 25 · answered Oct 03 '22 at 13:17

This error usually occurs because jdk is not selected for the project. I had the same problem and this worked for me.

Make sure that your class file is inside src folder then follow below steps

Step 1: Right click on project folder Step 2: Build Path --> Configure Build Path Step 3: Select "Java Build Path" from the left corner of the window Step 4: Under "Order and Export" Tab Step 5: Click on any of the jdk available check box to select it. Step 6: Click on Apply and Close.

Error: Selection does not contain a main type

25 Answers25

Solution - 2

Linked

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