Static block is not executing in JDK 7, "Main method not found", but works in JDK 1.5

Question

I have written a simple class with one static block

class Hello
{

  static {
           System.out.println("Hello");
       System.exit(0);
     }
}

When i am running it using jdk1.5, static block is getting executed

C:\apps\Java\jdk1.5.0_21\bin>javac Hello.java

C:\apps\Java\jdk1.5.0_21\bin>
C:\apps\Java\jdk1.5.0_21\bin>
C:\apps\Java\jdk1.5.0_21\bin>
C:\apps\Java\jdk1.5.0_21\bin>java Hello

Hello

But when i am running it using jdk1.7, i am getting following error

C:\Program Files (x86)\Java\jdk1.7.0_02\bin>
C:\Program Files (x86)\Java\jdk1.7.0_02\bin>javac Hello.java

C:\Program Files (x86)\Java\jdk1.7.0_02\bin>java Hello
Error: Main method not found in class Hello, please define the main method as:
    public static void main(String[] args)

Can anyone have any idea about this change of behaviour in JDK 5 and JDK 7?

Thanks in advance!!

Answer 1

Java 7 looks for a main method before loading the class. This is a behavior change from previous java versions and hence your static block is not executing. In previous versions, the behavior was that JRE used to look for main method post loading the class and after executing the static blocks.