I want to create a String array containing multiple empty strings.
String[] array = {"", "", "", "", ""};
In python we could achieve this simply with this code [""] * 5.
Is there something similar for java?
-
Isn't this code working?Farhan Qasim– Farhan Qasim2018-04-17 13:38:18 +00:00Commented Apr 17, 2018 at 13:38
-
@FarhanQasim the code is working. But if I want to initialize an array with 100 empty strings I don't want to write it by hand...user9483860– user94838602018-04-17 13:44:16 +00:00Commented Apr 17, 2018 at 13:44
Add a comment
|
6 Answers
Nothing syntactic, no.
At an API level, there's Arrays.fill, but sadly it doesn't return the array you pass it, so you can't use it in the initializer, you have to use it after:
String[] array = new String[5];
Arrays.fill(array, "");
You could always roll-your-own static utility method of course.
public static <T> T[] fill(T[] array, T value) {
Arrays.fill(array, value);
return array;
}
then
String[] array = YourNiftyUtilities.fill(new String[5], "");
(Obviously, it would probably be dodgy to do that with mutable objects, but it's fine with String.)
2 Comments
T.J. Crowder
@JohnyDoe: Because every entry in the array will refer to the same object. With mutable objects, that's not usually what you want (although it certainly can be), since you usually don't want
array[0].property = value to mean that array[1].property now has that value (because array[0] and array[1] refer to the same object). But Strings are immutable (modulo unreasonable games with reflection) so there's no such concern here.With Java 8, you have a not-so-concise, yet better-than-repeated-literals idiom:
// will create a String[] with 42 blank Strings
String[] test = Stream
// generate an infinite stream with a supplier for empty strings
.generate(() -> "")
// make the stream finite to a given size
.limit(42)
// convert to array with the given generator function to allocate the array
.toArray(String[]::new);
Comments
You can use the fill method from the Arrays class.
String[] test = new String[10];
Arrays.fill(test, "");
answered Apr 17, 2018 at 13:41
Federico klez Culloca
27.3k17 gold badges61 silver badges102 bronze badges
3 Comments
CodeFinity
Duplicate answer, now? Also, it's
Arrays, no?Federico klez Culloca
@CodeFinity fixed it. Thanks for pointing that out.
CodeFinity
🆒 And for completeness, the import is:
import java.util.Arrays;The closest would be
String[] array = new String[5];
Arrays.fill(array, "");
however it's not strictly the same as the array would first be initialised with null values.
Comments
You could try cycle:
String[] array = new String[5];
for (int i = 0; i < 5; i++)
array[i] = "";
2 Comments
T.J. Crowder
Bad idea to hardcode the
5 in two different places.
Raimund Krämer
Better use
array.length.Another approach would be to use IntStream.rangeClosed to generate the required amount of strings.
String[] result = IntStream.rangeClosed(1, 5)
.mapToObj(i -> "")
.toArray(String[]::new);
