A main() method is an entry point to start the execution of a program. Every Java application has at least one class and at least one main method.

Normally, an application consists of many classes and only one of the class needs to have a main method. 

The syntax for declaration of the java main method is as follows:
Syntax:
        public static void main(String[] args)
        {
            // Method body goes here.
        }

In the above declaration, two modifiers such as public, and static has been used with the main method. Let’s see a brief explanation and purpose of each of the terms used in the main method. 

1. public: The public modifier makes it accessible from anywhere in the application.

2. static: The static modifier makes it a class method so that it can be called using the class name without creating an object of the class.

3. void: The return type of the main method is void which means that it does not return a value to its caller.  You must specify void when you declare the main method. 


4. main: It is the name of a method where execution will start. In Java, the main method is called by JVM.

5. String[ ] args: The main method accepts one argument of type String array (String[ ]). The square brackets [ ] represent the array of strings that is passed as an argument to this method. args is the name of its parameter. You can use any parameter name as you wish.

For example, you can declare the main method like this public static void main(String[] myParameter), which is the same as declaring the main method as shown previously.

6. ( { ): This is an opening brace that marks the beginning of the main method body. It must be paired with a closing brace.

7. main Method Body: The region between the opening brace and closing brace is called main method body that contains a set of program statements. This region is static region.

8. ( } ): This is a closing brace that marks the closing of the main method body. It must be paired with an opening brace.

Why public static void main in Java?

Why do we need to declare main method as static in Java?

public class MainTest 
{ 
 public static void main(int a)
 { 
   System.out.println("Second main() method"); 
    main(); 
 } 
public static void main()
{ 
   System.out.println("Third main method"); 
 } 
public static void main(String[] args) 
{ 
   System.out.println("main(String[] args)"); 
     main(20); 
 } 
}

Output: 
        main(String[] args) 
        Second main() method 
        Third main method

public class A
{ 
  static 
  { 
     System.out.println("Static block is executed"); 
     System.exit(0); 
   } 
}

Key points: 
If the main() method has no argument of array reference of string type, the program source code will be compiled successfully without generating any error but at runtime, the program will terminate by generating an exception named: “NoSuchMethodError: main”.

Can we overload main method in java?

class OverloadMainMethod 
{ 
  public static void main(int a) // Overloaded main method 
  { 
     System.out.println(a); 
  } 
public static void main(String args[]) 
{ 
   System.out.println("main method invoked"); 
     main(10); 
 } 
}

Output: 
        main method invoked 
        10

Hope that this tutorial has covered almost all the important points related to Java main() method. I hope that you will have understood and enjoyed this tutorial.
Thanks for reading!!!
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