Concatenating elements in an array to a string

Question

I\'m confused a bit. I couldn\'t find the answer anywhere ;(

I\'ve got an String array:

String[] arr = [\"1\", \"2\", \"3\"];

then

Answer 1

Using Guava's Joiner (which in r18 internally uses StringBuilder)

String[]  arr= {"1","2","3"};
Joiner noSpaceJoiner = Joiner.on("");
noSpaceJoiner.join(arr))

Joiner is useful because it is thread-safe and immutable and can be reused in many places without having to duplicate code. In my opinion it also is more readable.

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Using Java 8's Stream support, we can also reduce this down to a one-liner.

String concat = Stream.of(arr).collect(Collectors.joining());

Both outputs in this case are 123