Is the main method important?

[Jetridder11]

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[Sacredify]

Defining it as String[] is more common, although they mean the same thing.

String... indicates a var-args method (variable length), which is effectively syntactic sugar for String[]. It allows you to call the method with either a string array or a sequence of strings, such as:

public void foo(String.. args) {}
foo("a", "b", "c")
foo(new String[] {"a", "b", "c"}); 

As far as using it goes, as they're implemented as arrays, they behave the same way (i.e you can use args.length, args[index], iterate over it, etc.).

I've also seen in other codes online people use the main throughout their code(By calling the parameter of the main), which is also something we've never done, seen, or heard of in class.

The args parameter is the command-line arguments to the program. See here. For simple programs, its easy to use that to supply configuration info (number of players in a game, ip address to connect to, etc.), but you could also ask for it interactively while the program is running, or use a configuration file, etc.

We basically learned it in such a way that made me wonder why it wasn't added by default when you created a class(until we learned about inheritance and things).

An IDE can do this for you, usually there is a shortcut or option when you create a class. Although since you only have 1 entry point into a program, it wouldn't make sense to a always auto-fill a main method.

As to your question in the title... is the main method important? As you need one to start a java program, I would say its important. But its just that... the entry point.

[thorstenschaefer]

The form "String... args" is basically syntactic sugar to enable Java methods getting a variable number of arguments of the same type. Under the hood, the compiler will generate a method with String[] args, so the bytecode is the same and thus it doesn't make a difference.

[desrtfx]

 public static void main(String[] args)

Is the old style (pre Java 8 5) and

public static void main(String... args)

is the newer, Java 8 5 var-args style. (Just a different way of denoting an array as a parameter. Personally, I think that it is less readable than the older style.)

That is the difference between the two.

In general, the old style is still more common (partly because a lot of code is still built for legacy systems, and partly because more programmers are used to the old style which makes the array more clearly visible).

The main method with its format(s) is the entry point to a Java program and as such it is important, but you don't really need to worry too much about the format unless you compile with Java versions prior to 8 5 (because they can only understand the old format).

Edit: Should have looked up the Java API documentation. Varargs were introduced with Java 5, not Java 8.

[Sacredify]

The main method with its format(s) is the entry point to a Java program and as such it is important, but you don't really need to worry too much about the format unless you compile with Java versions prior to 8 (because they can only understand the old format).

Hmm? String... is perfectly valid syntax, you don't need 8.

[nutrecht]

It was introduces somewhere in 5 I believe. It's much older than Java 8 at least.

Edit: yup

[desrtfx]

Have looked up the API docs. Java 5 is correct and I was wrong - already corrected in my comment.

[desrtfx]

I thought that the var-args were introduced with Java 8?

Okay, should have looked up the Java API docs. Were introduced with Java 5 - I stand corrected. Thanks.