正则表达式模式将逗号分隔的字符串转换为点分隔的一个

Question

I want to convert an long array values to a specific format of string.

for eg longArray = {0,1,2,3} to be converted as string 0.1.2.3

I can do Arrays.toString(longArray) which will return [0, 1, 2, 3].

Now this string [0,1,2,3] has to be converted into 0.1.2.3

I have used this code which works but would like to see if this code can be improved

String convertedString = Arrays.toString(longArray).replaceAll(",",".").replaceAll("[\\[,\\],\\s]", "");

I have to mention that i am on Java 7 so can't use any Java 8 features like streams Best Regards,

Saurav

Answer 1

    long[] longArray = {0,1,2,3};
    String s = LongStream.of(longArray)
            .mapToObj(Long::toString)
            .collect(Collectors.joining("."));

Array of longs to stream of longs, every long mapped to a String with Long.toString(long) and then joined with a delimiter . .

Originally I has String::valueOf instead of Long.toString . Thanks to @Andreas for a slightly better style.

Answer 2

Not much shorter, but I think the regular expressions make it look more elegant:

String convertedString = Arrays.toString(longArray)
.replaceAll("^.|.$", "");
.replaceAll("[^0-9]+",".")

1. Remove first and last character.
2. Replace all non-numeric strings with dots.