java 101, how do I count the number of arguments passed into main?

Question

For example

public static void main(String[] args) {
            int count = 0;
        for (String s: args) {
            System.out.println(s);
                count++;

        }

    }

is there some way of doing something like

int count = args.length()? or args.size()?

As everyone else has said, args.length is better. This is because the method of counting, while 100% valid, takes `n` loops, where `n` is the length of the array, whereas accessing args.length takes `1` loop, making it far faster. You can't change the `length` field, but you can still access it (we call this "final"). — Ryan Amos, Jul 25 '12 at 14:21
So many duplicate answers. Do we really need 6 answers for using array's `length` field? — Steve Kuo, Jul 25 '12 at 16:20

score 18 · Accepted Answer · answered Jul 25 '12 at 14:19

18

It would be:

int count = args.length;

answered Jul 25 '12 at 14:19

jrad

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Thanks, I was getting errors using args.length() with the brackets. I didn't see any reason why I should be able to do that. Silly mistake, thanks. – user1464251 Jul 25 '12 at 14:24
Arrays are special in Java, and carry `length` as a member field rather than a method call, so no parentheses. When using the [Java Collections](https://en.wikipedia.org/wiki/Java_collections_framework), such as `ArrayList`, you would be calling the [`size()`](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/Collection.html#size()) method, and parentheses are required. Now that I think about it, it would be worth filing a feature-request to ask that a `size()` method be added to arrays, as syntactic sugar, just for the sake of consistency and convenience. – Basil Bourque Feb 26 '19 at 20:16

score 4 · Answer 2 · answered Jul 25 '12 at 14:19

4

is there some way of doing something like

int count = args.length()? or args.size()?

Yes, args.length.

There is nothing special about args; it is a regular array of String objects and may be treated as such.

answered Jul 25 '12 at 14:19

Jon Newmuis

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score 2 · Answer 3 · answered Jul 25 '12 at 14:19

2

All arrays have a "field" called length

int count = args.length;

answered Jul 25 '12 at 14:19

Peter Lawrey

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score 2 · Answer 4 · answered Jul 25 '12 at 14:20

2

public static void main(String[] args) {
    System.out.println(args.length);
}

answered Jul 25 '12 at 14:20

Devin Hurd

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6

Cristiano Fontes · Answer 5 · 2012-07-25T14:25:23.550

2

"args" is just an array, so you can use it's length property.

Like this:

System.out.println(args.length);

and you are good to go.

edited Jul 25 '12 at 14:25

answered Jul 25 '12 at 14:20

Cristiano Fontes

4,920
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score 1 · Answer 6 · answered Jul 25 '12 at 14:41

1

Simply use
int length=args.length

args is simply an array and you can use it's length property.

answered Jul 25 '12 at 14:41

Sumit Desai

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java 101, how do I count the number of arguments passed into main?

6 Answers6