Main-Method

The main method is the entry point of any standalone Java application. When you run a Java program, the Java Virtual Machine (JVM) looks for the main method and starts executing your program from there.

Syntax of main method

public static void main(String[] args) {
// your code here
}

Explanation of each part:

• public: The method is accessible from anywhere. This is required because the JVM needs to invoke it from outside your class.so JVM can access the method/class from anywhere.
• static: Allows JVM to call main without creating an object of the class.
• void: Means the main method does not return anything.
• main: This is the name of the method that the JVM looks for.
• String[] args: An array of String objects. It is Used for command-line arguments. It lets your program accept command-line arguments passed as strings when you run the program.

How the main method works

When you run a Java application:

1. The JVM loads the class you designated to run.
2. It looks for a public static void main(String[] args) method.
3. It executes the statements inside the main method.
4. Your program runs until the main method finishes or the program exits (e.g., via System.exit()).

Example

public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello, world!");

        // Print all command-line arguments
        for (String arg : args) {
            System.out.println("Arg: " + arg);
        }
    }
    }

Run with command-line arguments:

java HelloWorld first second third

Output:

Hello, world!
Arg: first
Arg: second
Arg: third

Notes

• Without a proper main method, the JVM will not run your class as a standalone application and will give an error.
• The main method must be declared exactly as shown, otherwise the JVM won't recognize it.
• You can overload the main method by defining other methods named main with different parameters, but the JVM only calls the standard signature.

Summary

The main(String[] args) method is the required starting point of every Java standalone program. It acts as a bridge between the JVM and your application code.