Unable to run Java code with Intellij IDEA

Question

I have just downloaded the IDE  and I want to edit my first Java file with it  I m not interested in creating a whole project  just editing the single file   So I opened the file from my desktop with Intellij IDEA as I set it as my default program for opening  java files   I write some code and the main run and debug buttons are greyed out  I can t run my code   I have already installed Java 8 update 45 64-bit  I have a 64 bit OS  as well as the Java development kit  J8U45   I have set my global IDE SDK as my JDK installation  and when it prompts me I also set this as my project SDK  but still the run and debug buttons are unable to be used   Edit  I am also unable to run my file regardless of if its in a project or not   Edit 2  Screenshot of my project setup

User · Answer

right click on the  SRC folder   select  Mark directory as   select  Resource Root    Then Edit the run configuration  select Run  run  edit configuration  with the plus button add an application configuration  give it a name  could be any name   and in the main class write down the full name of the main java class for example  com example java MaxValues   you might also need to check file  project structure  project settings-project  give it a folder for the compiler output  preferably a separate folder  under the java folder

User · Answer

Don t forget the String   args in your main method  Otherwise  there s no option to run your program   public static void main String   args

User · Answer

Move your code inside of the src folder   Once it s there  it ll be compiled on-the-fly every time it s saved   IntelliJ only recognizes files in specific locations as part of the project - namely  anything inside of a blue folder is specifically considered to be source code   Also - while I can t see all of your source code - be sure that it s proper Java syntax  with a class declared the same as the file and that it has a main method  specifically public static void main String   args     IntelliJ won t run code without a main method  rather  it can t - neither it nor Java would know where to start

User · Answer

My classes contained a main   method yet I was unable to see the Run option  That option was enabled once I marked a folder containing my class files as a source folder    Right click the folder containing your source Select Mark Directory as  rarr  Test Source Root   Some of the classes in my folder don t have a main   method  but I still see a Run option for those

User · Answer

If you use Maven  you must to declare your source and test folder in project directory    For these  click F4 on Intellij Idea and Open Project Structure  Select your project name on the left panel and Mark As your  Source  and  Test  directory

User · Answer

If you can t run your correct program and you try all other answers Click on Edit Configuration and just do following steps-    Click on add icon and select Application from the list  In configuration name your Main class  as your main class name  Set working directory to your project directory  Others  leave them default and click on apply  Now you can run your program enter image description here

User · Answer

Something else that worked for me    Right click the folder in src containing your main  You ll see an option  run  file main     with the run icon   Click it  and then the run icon in the top right and bottom left will turn green from then on

User · Answer

Last resort option when nothing else seems to work  close and reopen IntelliJ   My issue was with reverting a Git commit  which happened to change the Java SDK configured for the Project to a no longer installed version of the JDK  But fixing that back still didn t allow me to run the program  Restarting IntelliJ fixed this

User · Answer

-First Move Your Code Files in side the  src  Folder  -Make sure your Main method is declared like the following     public class Main            public static void main String   args                      then     Go to Project configurations select Java application  check allow parallel run and select your main class   and it should work

User · Answer

Sometimes  patience is key   I had the same problem with a java project with big node modules    m2 directories  The indexing was very long so I paused it and it prevented me from using Run Configurations   So I waited for the indexing to finish and only then I was able to run my main class

User · Answer

I had the similar issue and solved it by doing the below step    Go to  Run  menu and  Edit configuration  Click on add    icon and select Application from the list  In configuration name your Main class  name of your main class  Working Directory   It should point till the src folder of your project  C  Users name Work ProjectName src  This is where I had issue and after correcting this  I could see the run option for that class

User · Answer

If you are just opened a new java project then create a new folder src  in the man project location   Then cut and paste all your package in that folder   Then Right click on src directory and select option Mark Directory As   Sources Root

[java] Unable to run Java code with Intellij IDEA

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