Reputation: 4740

Editor does not contain a main type

Just going through the sample Scala code on Scala website, but encountered an annoying error when trying to run it.

Here's the code: http://www.scala-lang.org/node/45. On running it on Eclipse, I got this message 'Editor does not contain a main type' that prevents it from running.

Is there anything I need to do...i.e break that file into multiple files, or what?

Upvotes: 94

Answers (30)

Abdelhadi Lahlou

Reputation: 525

This is an easy way to solve it:

Right click on source folder -> Build Path -> Remove from Build Path
Right click on source folder -> Build Path -> use as source folder

Upvotes: 0

Mohit Singh

Reputation: 6167

Just close and reopen your project in Eclipse. Sometime there are linkage problems. This solved my problem

Upvotes: 6

static

Reputation: 321

A simpler way is to close the project and reopen it.

Upvotes: 32

kholofelo Maloma

Reputation: 1003

Just make sure that the folder you work in is added to the built path:

right-click your folder --> build Path --> Use as source Folder

and it should now find main therein.

Upvotes: 23

Manpreet gujral

Reputation: 1

Add a main method method inside the class to overcome this problem. I was facing the same issue regarding this.Now Including the main method inside my code i resolved my problem.

Upvotes: -1

Mahesh Karoshi

Reputation: 1

Instead of adding File, add class. File->New->Class. That fixed my issue.

Upvotes: -1

Naresh

Reputation: 31

Have faced the similar issue, resolved this by right clicking on the main method in the outline view and run as Java application.

Upvotes: 3

ssomu

Reputation: 89

If it is maven project please check the java file is created under src/main/java

If you are not getting please change the JRE path and create the java files in above folder structure

Upvotes: 1

Anand Dhole

Reputation: 83

I had the same problem. I tried all sorts of things. And I came to know that

My .java files were not linked and
they were not placed in the 'src' folder.

Things I did:

Project properties >> Java Build Path >> Source

Deleted the original 'src' folder which was empty using 'Remove' option
Added the source that contained my source .java files using the 'Add Folder' option

This solved the error.

Upvotes: 7

AalekhG

Reputation: 381

This could be the issue with the Java Build path. Try below steps :

Go to project properties
Go to java Build Path
Go to Source tab and add project's src folder

This should resolve the issue.

Upvotes: 1

WantaBeCoder

Reputation: 1

On reason for an Error of: "Editor does not contain a main type"

Error encountered in: Eclipse Neon

Operating System: Windows 10 Pro

When you copy your source folders over from a thumb-drive and leave out the Eclipse_Projects.metadata folder.

Other than a fresh install, you will have to make sure you merge the files from (Thrumb-drive)F:Eclipse_Projects.metadata.plugins .

These plug-ins are the bits and pieces of library code taken from the SDK when a class is created. I really all depends on what you-----import javax.swing.*;----- into your file. Because your transferring it over make sure to merge the ------Eclipse_Projects.metadata.plugins------ manually with a simple copy and paste, while accepting the skip feature for already present plugins in your Folder.

For windows 10: you can find your working folders following a similar pattern of file hierarchy.

C:Users>Mikes Laptop> workspace > .metadata > .plugins <---merge plugins here

Upvotes: 0

nuriaion

Reputation: 2631

I have this problem a lot with Eclipse and Scala. It helps if you clean your workspace and rebuild your Project.

Sometimes Eclipse doesn't recognize correctly which files it has to recompile :(

Edit: The Code runs fine in Eclipse

Upvotes: 38

MikeG

Reputation: 11

run "eclipse -clean -refresh" from command line. This fixed the issue for me when all other solutions failed.

Upvotes: 1

Vlad.Bachurin

Reputation: 1358

In my particular 'Hello World' case the cause for this problem was the fact, that my main() method was inside the Scala class.

I put the main() method under the Scala object and the error disappeared.

That is because Scala object in Java terms is the entity with only static members and methods inside.

That is why Java's public static void main() in Scala must be placed under object.

(Scala class may not contain static's inside)

Upvotes: 0

George Santhosh

Reputation: 119

Try 'Update Project'. Once I did this, The Run as Java Application option appeared.

Upvotes: 0

jacruz

Reputation: 56

I had the same problem. I had the main class out of the src package, in other folder. I move it in and correct folder and solved

Upvotes: 1

Fei

Reputation: 591

You can try to run the main function from the outline side bar of eclipse.

solution

Upvotes: 8

Hunsu

Reputation: 3381

I have this problem too after I changed the source folder. The solution that worked for is just editing the file and save it.

Upvotes: 0

Sahil Pruthi

Reputation: 55

Make sure that your .java file is present either in the str package, or in some other package. If the java file with the main function is outside all packages, this error is thrown.

Upvotes: 3

Vamsi Tallapudi

Reputation: 3953

May be the file you have created is outside the src(source) folder. Trying to call the class object(from the file located in the src folder) from the .java file outside the source folder results in the same error. Copy .java file to the source folder, then build it. The error will be gone.

Upvotes: 1

user2704136

Reputation: 29

I had this problem with a Java project that I imported from the file system (under Eclipse Helios). Here's a hint: the src code didn't seem to be compiled at all, as no "bin" directory showed up.

I had to create a Java project from scratch (using the wizard), then compare the .project files of the non-working and working projects.

The project giving "Editor does not contain a main type" had this as the "buildSpec" in the .project file:

<buildSpec>
</buildSpec>

But the working project had this as the "buildSpec":

<buildSpec>
    <buildCommand>
        <name>org.eclipse.jdt.core.javabuilder</name>
        <arguments>
        </arguments>
    </buildCommand>
</buildSpec>

I copied this in, and the imported project worked.

I know my answer is for Java, but the same might be the issue for your Scala project.

Upvotes: 1

Daniel Ashton

Reputation: 1438

One more thing to check: make sure that your source file contains the correct package declaration corresponding to the subdirectory it's in. The error mentioned by the OP can be seen when trying to run a "main type" declared in a file in a subdirectory but missing the package statement.

Upvotes: 0

Mike

Reputation: 1

File >> Import >> Existing Projects into Workspace >> Select Archive Filed >> Browse and locate file >> Finish. If its already imported some other way delete it and try it that way. I was having the same problem until i tried that.

Upvotes: 0

Mani Kandan

Reputation: 1

Follow the below steps:

Backup all your .java files to some other location
delete entire java project
Create new java project by right click on root & click new
restore all the files to new location !!

Upvotes: 0

Sergiu

Reputation: 369

In the worst case - create the project once again with all the imports from the beginning. In my case none of the other options worked. This type of error hints that there is an error in the project settings. I once managed to solve it, but once further developments were done, the error came back. Recreating everything from the beginning helped me understand and optimize some links, and now I am confident it works correctly.

Upvotes: 0

ultra99

Reputation: 413

You have to make sure that your .java files are in the .src folder in eclipse. I had the same exact problem until I got it figured out.

Upvotes: 28

do quang nhat

Reputation: 1

You need locate file .java in folder src (in Project Explorer of Eclipse) and then it run. I have just add a file .java into project and it isn't in folder src, so I have a same error. I put again it into src, then it was build.

Upvotes: -1

vijaya

Reputation: 31

you should create your file by

selecting on right side you will find your file name,

under that will find src folder their you right click select -->class option

their your file should be created

Upvotes: 3

AbsintheSyringe

Reputation: 41

What you should do is, create a Java Project, but make sure you put this file in the package file of that project, otherwise you'll encounter same error.

enter image description here

Upvotes: 4

djangofan

Reputation: 29669

For me, in Eclipse 3.6, this problem occurs when my main method is not public. I caused the problem by having a main method like this:

static void main(String[] args)

The dubugger was unable to detect this by itself. I am pretty suprised Eclipse overlooked this.

Upvotes: 0

Editor does not contain a main type

Answers (30)

Related Questions