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How to execute a java program without having a main () method


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How to execute a java program without having a main () method: 




In Java, Up to Java 6 it was possible to do this using the Static Initialization Block. For solve the problem to a execute java program without having main method.


For example we have writing the following code using static block:

 

 

public class CheckWithoutMain{ 

  static{ 

  System.out.println("static block is Executed"); 

  System.exit(0); 

  } 

 

Output: (In JDK 6)





The System.exit (0); is used to the program exit before the JVM is looking for the main method, otherwise error will be thrown:


Exception in thread “main” java.lang.NoSuchMethodError:main

 

In Java 7 & above, however, this does not work anymore, even though it compiles, the following error will appear when you try to execute it:

The program compiled successfully, but main class was not found. Main class should contains method: public static void main (String [] args).


Output: (In JDK 8)



 

So, we have only execute a java program without having main method up to valid Java versions 6.


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