Is main method compulsory in Java?

1.5

The answer to this question depends on version of java you are using. Prior to JDK 5, main method was not mandatory in a java program.

  • You could write your full code under static block and it ran normally.
  •  
    However, From JDK6 main method is mandatory. If your program doesn’t contain main method, then you will get a run-time error “main method not found in the class”. Note that your program will successfully compile in this case, but at run-time, it will throw error.

    // This program will successfully run
    // prior to JDK 5
    public class Test 
    {
    	// static block
    	static
    	{
    		System.out.println("program is running without main() method");
    	}
    }
    

    Output:

  • If run prior to JDK 5
    program is running without main() method
    
  • If run on JDK 6,7,8
    Error: Main method not found in class Test, please define the main method as:
       public static void main(String[] args)
    
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