Java: Copy array of Integers into Array of Strings

Question

Consider a method whose signature contains an Integer Array:

public static void parse(Integer[] categories)

parse needs to call a different method, which expects an Array of Strings. So I need to convert Integer[] to String[].

For example, [31, 244] ⇒ ["31", "244"].

I've tried Arrays.copyOf described here:

String[] stringArray = Arrays.copyOf(objectArray, objectArray.length, String[].class);

But got an ArrayStoreException.

I can iterate and convert each element, but is there a more elegant way?

It's not a problem, but I thought there would be something more elegant, perhaps reminiscent of Python's list comprehension. — Adam Matan, Feb 27 '12 at 12:02
either way the bottom line is that java has to convert each element separately, so any way you can find may just look nicer, but executes a loop — Hachi, Feb 27 '12 at 12:07

anubhava · Accepted Answer · 2015-10-07T10:45:45.770

3

If you're not trying to avoid a loop then you can simply do:

String[] strarr = new String[categories.length];
for (int i=0; i<categories.length; i++)
     strarr[i] = categories[i] != null ? categories[i].toString() : null;

EDIT: I admit this is a hack but it works without iterating the original Integer array:

String[] strarr = Arrays.toString(categories).replaceAll("[\\[\\]]", "").split("\\s*,\\s*");

edited Oct 07 '15 at 10:45

answered Feb 27 '12 at 12:03

anubhava

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-1 the question is: "I can iterate and convert each element, but is there a more elegant way?" – Massimiliano Peluso Feb 27 '12 at 12:10
I gave it a +1, not accepted it. And it might be the right answer if there isn't any one-liner. – Adam Matan Feb 27 '12 at 12:13
so the right answer is something that you already knew isn't it? – Massimiliano Peluso Feb 27 '12 at 12:24
@MassimilianoPeluso: Pls check the **EDIT** section. Not sure about the elegance but it avoids the iteration of the original array. – anubhava Feb 27 '12 at 14:01
I'm pretty much convinced that iterating is the Javaesque way. Thanks! – Adam Matan Feb 27 '12 at 14:09
1

The second solution adds extraneous spaces to all string elements with an index greater than 0. – simon Oct 07 '15 at 10:38
1

@simon: `.split("\\s*,\\s*");` will strip all spaces. – anubhava Oct 07 '15 at 10:45

score 1 · Answer 2 · answered Feb 27 '12 at 12:02

You could do it manually by iterating over the Int-Array and saving each element into the String-Array with a .toString() attached:

for(i = 0; i < intArray.length(); i++) {
    stringArray[i] = intArray[i].toString()
}

(Untested, but something like this should be the thing you are looking for)

Hmmm, just read your comment. I don't know any easier or more elegant way to do this, sorry.

score 1 · Answer 3 · answered Feb 27 '12 at 12:04

1

i don't think that theres a method for it:

use a loop for it like:

String strings[] = new String[integerarray.length];

for(int i = 0; i<integerarray.length;++i)
{
     strings[i] = Integer.toString(integerarray[i]);
}

answered Feb 27 '12 at 12:04

fnobbi

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Java: Copy array of Integers into Array of Strings

3 Answers3