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Lesson 4 The main() method
Objective Main() method as an entry point

Java main() method


Use of the main() method as an entry point.

The main() method is the entry point for a Java program.
It is the first method that is invoked when a Java program is run.
A correctly defined main() method has the following signature:
  1. Naming context :A context or scope in which identifiers are unique.
  2. Signature: The name of the method and the number and types of formal parameters to the method.
main
method on the exam
public static void main(String[] args) {
 // The statements of the method are put here.
}


The modifiers public and static , and the void return type must precede the main() method name. The main() method has a single argument that is an array of String objects. The args identifier is used by custom as the argument name.
However, any other valid identifier may be used in place of args .
Modifier: A keyword that is used to modify the definition of a class, variable, method, or constructor.
Only Java application programs need a main() method. Applets are not required to have a main() method since they are executed by browsers within the context of a Web page.
The argument of the main() method provides access to the program's command line arguments. For example, suppose that a program is invoked with command line arguments of abc , def , and ghi. Then args[0] would reference the String "abc" , args[1] would reference "def" , and args[2] would reference "ghi" .
The MainTest program provides an example of using the main() method to access command line arguments.