[FLINK-3886] Give a better error when the application Main class is not public.

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.1.0
• Assignee: Niels Basjes
• Reporter: Niels Basjes
• Created: 09/May/16 14:40
• Updated: 31/May/16 15:52
• Resolved: 31/May/16 15:51

Description

I wrote a Flink application and made the simple mistake of making the Main class 'package private' by simply writing it as (note: I simply forgot the 'public' keyword)

class Main {
   ...
}

The error you get is:

Caused by: java.lang.IllegalAccessException: Class org.apache.flink.client.program.PackagedProgram can not access a member of class com.bol.experiment.flink.Main with modifiers "public static"
	at sun.reflect.Reflection.ensureMemberAccess(Reflection.java:102)
	at java.lang.reflect.AccessibleObject.slowCheckMemberAccess(AccessibleObject.java:296)
	at java.lang.reflect.AccessibleObject.checkAccess(AccessibleObject.java:288)
	at java.lang.reflect.Method.invoke(Method.java:490)
	at org.apache.flink.client.program.PackagedProgram.callMainMethod(PackagedProgram.java:505)

This took me 30 minutes to figure out what I did wrong.
I think the error message should be more explanatory to the developer.

Issue Links

• links to: GitHub Pull Request #2043