Iterate over static array in java without array variable

Question

In Ruby, I can do something like:

["FOO", "BAR"].each do { |str| puts str }

Iterating over an array defined in the statement in which I'm using it. Since I can define an array in Java like:

String[] array = { "FOO", "BAR" };

I know I can avoid defining the variable by setting up a loop like:

for (String str : new String[] { "FOO", "BAR" }) { ... }

But, I was hoping java might have something more terse, WITHOUT defining a variable containing the array first, and also allow me to avoid the dynamic allocation, is there a syntax like:

for (String str : { "FOO", "BAR" }) { ... }

That is more terse that will work with Java that I'm missing, or is the solution I've got above my only option?

Good question. It would be interesting to see if there's any easier way to define literal data structures. — feralin
– feralin, Commented Jul 3, 2013 at 16:41
Just found this (nearly identical) question while surfing: stackoverflow.com/questions/2358866/… — Xaq
– Xaq, Commented Jul 3, 2013 at 17:07

sanbhat · Accepted Answer · 2013-07-03 16:42:55Z

10

The best you can do is

    for(String s : Arrays.asList("a", "b")) {
        System.out.println(s);
    }

java.util.Arrays gives a method asList(...) which is a var-arg method, and it can be used to create List (which is dynamic array) on fly.

In this way you can declare and iterate over an array in same statement

answered Jul 3, 2013 at 16:42

sanbhat

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1 Comment

stwr667 Over a year ago

Since Java 11, you can replace Arrays.asList with List.of. And also String with var, because the type can be inferred from the types in the list.

kamwo · Accepted Answer · 2015-07-28 11:09:30Z

6

In Java 8, you will be able to do the following:

Stream.of("FOO", "BAR").forEach(s -> System.out.println(s));

This uses the new java.util.stream package and lambda expressions.

edited Jul 28, 2015 at 11:09

kamwo

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answered Jul 3, 2013 at 17:01

Jeffrey

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1 Comment

Xaq Over a year ago

Thanks -- I thought Java8 might add something like that.

Jashaszun · Accepted Answer · 2013-07-03 16:51:24Z

2

Languages like Java are incredibly verbose compared to terse languages like Ruby. It looks to me like what you already have is your best bet:

for (String str : new String[] { "FOO", "BAR" }) { ... }

answered Jul 3, 2013 at 16:51

Jashaszun

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Comments

Stephen Harrison · Accepted Answer · 2017-08-31 12:39:25Z

1

I think your question is about syntactic sugar for collections as much as anything. However, in Java 8 you can say

Arrays.asList("a", "b").forEach(System.out::println);

where you can of course substitute your own method literal that's compatible with Consumer<T>.

answered Aug 31, 2017 at 12:39

Stephen Harrison

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