Why Is public static void main(String[] args) Essential in Java Programs?

  • Java
  • Thread starter heman
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    Java
In summary, The first line in a Java program after the class name is "public static void main(String[] args)". This line is important because it is the starting point of the program's execution and is necessary for the program to run. The "void" keyword indicates that the method does not return a value. The "public" keyword allows the method to be accessed from outside the class, and "static" means that the method belongs to the class and not to an instance of the class. The "String[] args" is used to pass arguments to the program, which can be useful for controlling its behavior. This line is also necessary for a Java class to be runnable, and without it, the program will not compile. However,
  • #1
heman
361
0
As a very beginner to java a very basic question is in mind.in every java program we write the first line after mentioning the name of the class as

____________________________________

public static void main(String[] args)

_____________________________________

so i want to know the importance of this line and each component in this line because i am not getting to it.
i will be very thankful for urs help.
 
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  • #2
Main is the function from which program execution stars.void implies that the function doesn't return a value.The rest you can put off until later.public(after learning classes)statis(types of variables)
 
  • #3
Since you're beginning, you may not understand the significance of the "public static," but the String[] args may be useful to know. Those are some arugments to control how your program works.

Say you have a class "Circle." that looks something like this:

public class Circle
{

public static void main(String[] args)
{
drawCircle(args[0]);
}

void drawCircle(String a){...} //would contain code for drawing a circle of a certain color.

}

Upon calling your program, you'd need to tell the program what color you wanted. You would, for example, call "Circle blue," and it would draw a blue circle.
 
  • #4
It is method main() that makes a Java class runnable. You cannot run other Java classes that don't contain this method. The compiler will give a NoSuchMethodException.
A different case is with applets, where you don't have to declare main(). Execution starts with method init(), if any, or with paint().
 

1. What is a main method in Java and why is it important?

The main method is a special method in Java that serves as the entry point for a program. It is the first method that is executed when a program is run and it is responsible for starting the program's execution. It is important because without a main method, the program will not be able to run.

2. How do you declare a main method in Java?

To declare a main method in Java, you use the following syntax: public static void main(String[] args). This indicates that the method is public, static, does not return any value, and takes an array of strings as its arguments.

3. What is the purpose of the String[] args parameter in the main method?

The String[] args parameter in the main method is used to pass command-line arguments to a Java program. This allows for dynamic input into the program and allows it to be executed with different arguments each time.

4. Can a Java program have more than one main method?

No, a Java program can only have one main method. This is because the main method is the entry point for the program and having multiple entry points would cause confusion and make it difficult to determine which main method should be executed.

5. What happens if the main method is not declared as public or static?

If the main method is not declared as public or static, the program will not compile. This is because the main method must be accessible to other classes and it must be static so that it can be called without an instance of the class being created.

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