No Main class found in NetBeans

Question

I have been working on an assignment for my class in programming  I am working with NetBeans  I finished my project and it worked fine  I am getting a message that says  No main class found  when I try to run it  Here is some of the code with the main   package luisrp3  import java io FileNotFoundException  import java io PrintStream   public class LuisRp3    public static void main String   args  throws FileNotFoundException         java io File newFile   new java io File  LuisRamosp4 txt         if  newFile exists              newFile delete               System setOut new PrintStream newFile         Guitar guitar   new Guitar       I posted this before but had a couple issues  i have fixed the others and now have just this one remaining  Any advice will be greatly appreciated

User · Answer

Press the hammer to the left of the green arrow  run   for the program to clean  amp  build project  Press green arrow  Select Main Class   Hope it works for u

User · Answer

Make sure the access modifier is public and not private  I keep having this problem and always that s my issue   public static void main String   args

User · Answer

There could be a couple of things going wrong in this situation  assuming that you had code after your example and didn t just leave your code unbracketed    First off  if you are running your entire project and not just the current file  make sure your project is the main project and the main class of the project is set to the correct file   Otherwise  I have seen classmates with their code being fine but they still had this same problem  Sometimes  in Netbeans  a simple fix is to    Copy your current code  or back it up in a different location  Delete your current file Create a new main class in your project  you can name it the old one  Paste your code back in   If this doesn t work then try to clear the Netbeans cache  and if all else fails  then just do a clean un-installation and re-installation of Netbeans

User · Answer

The connections I made in preparing this for posting really cleared it up for me  once and for all  It s not completely obvious what goes in the Main Class  box until you see the connections   Note that the class containing the main method need not necessarily be named Main but the main method can have no other name

User · Answer

In the toolbar search for  press the arrow and select Customize    It will open project properties In the categories select RUN  Look for Main Class  Clear all the Main Class character and type your class name  Click on OK  And run again  The problem is solved

User · Answer

When creating a new project - Maven - Java application in Netbeans the IDE is not recognizing the Main class on 1st class entry   in Step 8 below we see no classes    When first a generic class is created and then the Main class is created Netbeans is registering the Main class and the app could be run and debugged   Steps that worked for me    Create new project - Maven - Java application  project created  mytest  package created  com me test  Right-click package  com me test New   Java Class   Named it  Whatever  you want Right-click package  com me test New   Java Main Class   named it   Main   must be  Main   Right click on Project mytest Click on Properties Click on Run   next to  Main Class  text box    Browse  You should see  com me test Main Select it and click  Select Main Class    Hope this works for others as well

User · Answer

You need to add    to the end of your code

User · Answer

Also  for others out there with a slightly different problem where Netbeans will not find the class when you want when doing a browse from  main classes dialog window      It could be that your main method does have the proper signature   In my case I forgot the args   example  public static void main String   args   The modifiers public and static can be written in either order  public static or static public   but the convention is to use public static as shown above    Args   You can name the argument anything you want  but most programmers choose  args  or  argv    Read more here  http   docs oracle com javase tutorial getStarted application

User · Answer

I had the same problem in Eclipse  so maybe what I did to resolve it can help you  In the project properties I had to set the launch configurations to the file that contains the main-method  I don t know why it wasn t set to the right file automatically

User · Answer

If the advice to add the closing braces work  I suggest adding indentation to your code so every closing brace is on a spaced separately  i e    public class LuisRp3        public static void main String   args  throws FileNotFoundException            stuff            This just helps with readability   If  on the other hand  you just forgot to copy the closing braces in your code  or the above suggestion doesn t work  open up the configuration and see if you can manually set the main class  I m afraid I haven t used NetBeans much  so I can t help you with where that option is  My best guess is under  Run Configuration   or something like that   Edit  See peeskillet s answer if adding closing braces doesn t work

User · Answer

In project properties  under the run tab  specify your main class   Moreover  To avoid this issue  you need to check  Create main class  during creating new project  Specifying main class in properties should always work  but if in some rare case it doesn t work  then the issue could be resolved by re-creating the project and not forgetting to check  Create main class  if it is unchecked

User · Answer

I also experienced Netbeans complaining to me about  No main classes found   The issue was on a project I knew worked in the past  but failed when I tried it on another pc   My specific failure reasons probably differ from the OP  but I ll still share what I learnt on the debugging journey  in-case these insights help anybody figure out their own unique issues relating to this topic   What I learnt is that upon starting NetBeans  it should perform a step called  Scanning projects       Prior to this phase  you should notice that any  java file you have with a main   method within it will show up in the  Projects  pane with its icon looking like this  no arrow      After this scanning phase finishes  if a main   method was discovered within the file  that file s icon will change to this  with arrow      So on my system  it appeared this  Scanning projects     step was failing  and instead would be stuck on an  Opening Projects  step   I also noticed a little red icon in the bottom-right corner which hinted at the issue ailing me     Unexpected Exception java lang ExceptionInInitializerError   Clicking on that link showed me more details of the error   java security NoSuchAlgorithmException  MD5 MessageDigest not available     at sun security jca GetInstance getInstance GetInstance java 159      at java security Security getImpl Security java 695      at java security MessageDigest getInstance MessageDigest java 167      at org apache lucene store FSDirectory  lt clinit gt  FSDirectory java 113  Caused  java lang RuntimeException     at org apache lucene store FSDirectory  lt clinit gt  FSDirectory java 115  Caused  java lang ExceptionInInitializerError     at org netbeans modules parsing lucene LuceneIndex DirCache createFSDirectory LuceneIndex java 839    That mention of  java security  reminded me that I had fiddled with this machine s  java security  file  to be specific  I was performing Salvador Valencia s steps from this thread  but did it incorrectly and broke  java security  in the process      Once I repaired the damage I caused to my  java security  file  NetBeans   Scanning projects     step started to work again  the little green arrows appeared on my files once more and I no longer got that  No main classes found  issue

User · Answer

You need to rename your main class to Main  it cannot be anything else   It does not matter how many files as packages and classes you create  you must name your main class Main   That s all

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import java util Scanner  public class FarenheitToCelsius      public static void main String  args        Scanner input  new Scanner System in        System out println  Enter Degree in Farenheit          double Farenheit input nextDouble           convert farenheit to celsius      double celsuis  5 0 9   farenheit 32        system out println  Farenheit  farenheit  is  celsius  in celsius

User · Answer

if all that is your code you forgot to close the main method  everything else sounds good to me  public class LuisRp3    public static void main String   args  throws FileNotFoundException         java io File newFile   new java io File  LuisRamosp4 txt         if  newFile exists              newFile delete               System setOut new PrintStream newFile         Guitar guitar   new Guitar          try that

User · Answer

Right click on your Project in the project explorer Click on properties Click on Run Make sure your Main Class is the one you want to be the entry point   Make sure to use the fully qualified name i e  mypackage MyClass  Click OK  Run Project      If you just want to run the file  right click on the class from the package explorer  and click Run File  or  Alt   R  F   or  Shift   F6

[java] No Main class found in NetBeans

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