Consider following Java program:

class GFG {
	public static void main(String args[])
	{
		System.out.println("GeeksforGeeks");
	}
}

Output:

GeeksforGeeks

Explanation:

1)public: It is an access specifier which allows the JVM(Java Virtual Machine) to access the main method from anywhere.

2)static: static keyword allows the JVM to access the main method without any instance(object).

3)void: It specifies that the main method doesn’t return anything.

4)main: name of the method(function) configured in JVM.

5)String args[]: Command line arguments.

Now, if we replace ‘public’ with ‘private’ in “public static void main”, the above code becomes:

class GFG {
	private static void main(String args[])
	{
		System.out.println("GeeksforGeeks");
	}
}

Explanation:

The above code will be compiled successfully, but will throw a runtime error as follows:

Error: Main method not found in class GFG, please define the main method as:
   public static void main(String[] args)
or a JavaFX application class must extend javafx.application.Application

Reason:

Since the access specifier was changed from “public” to “private” JVM was unable to access/locate the main method.