Why is main method public static and void in Java? Will the program compile, if the main method is not static?

Java program's main method has to be declared static because keyword static allows main to be called without creating an object of the class in which the main method is defined. If we omit static keyword before main Java program will successfully compile but it won't execute.

For a little detailed description, look at the usual signature of Java's main method

public static void main (String[] args)

Above code line begins defining the main method. This is the line at which the program will start executing. All Java applications begin execution by calling main.

The public keyword is an access specifier, which allows the programmer to control the visibility of class members. When a class member is preceded by public, then that member may be accessed by code outside the class in which it is declared. In this case, main must be declared as public, since it must be called by code outside of its class when the program is started. The keyword static allows main to be called without having to instantiate a particular instance of the class. Without having declared main method static, your program will successfully compile but won't execute and report error at run time. This is necessary since main is called by the Java interpreter before any objects are made. The keyword void simply tells the compiler that main does not return a value. The main is the method called when a Java application begins. Keep in mind that Java is case-sensitive. Thus, Main is different from main. It is important to understand that the Java compiler will compile classes that do not contain a main method. But the Java interpreter has no way to run these classes. So, if you had typed Main instead of main, the compiler would still compile your program. However, the Java interpreter would report an error because it would be unable to find the main method.

Hope you have enjoyed reading the reason why main in Java is declared public static and void. Please do write us if you have any suggestion/comment or come across any error on this page. Thanks for reading!




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is the main author for cs-fundamentals.com. He is a software professional (post graduated from BITS-Pilani) and loves writing technical articles on programming and data structures.

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