Editor does not contain a main type

Question

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

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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

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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

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That code is valid  Have you tried to compile it by hand using scalac  Also  have you called your file  addressbook   all lowercase  like the name of the object   Also  I found that Eclipse  for some reason  set the main class to be   addressbook  instead of  addressbook

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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

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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

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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

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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

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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

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I just had this problem too  The solution is to make sure eclipse created the project as Java project  Just create a new Java project and copy your class into the src folder  and import the eventual dependencies   This should fix the problem

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

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A simpler way is to close the project and reopen it

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In Eclipse  make sure you add your source folder in the project properties -  java build path -  source   Otherwise  the main   function may not be included in your project

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

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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

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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    lt buildSpec gt   lt  buildSpec gt    But the working project had this as the  buildSpec     lt buildSpec gt       lt buildCommand gt           lt name gt org eclipse jdt core javabuilder lt  name gt           lt arguments gt           lt  arguments gt       lt  buildCommand gt   lt  buildSpec gt    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

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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

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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

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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

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

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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

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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

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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

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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

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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  amp  click new restore all the files to new location

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A quick solution    First  exclude the package  Right click on the source package    Build Path    Exclude  Then include it back  Right click on the source package    Build Path    Include

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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

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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

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The correct answer is  the Scala library needs to before the JRE library in the buildpath     Go to Java Buildpath   Order and Export and move Scala library to the top

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

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

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

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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

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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  lt ---merge plugins here

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

[eclipse] Editor does not contain a main type

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