Splitting string selectively on tokens

Question

I am splitting my string about the word "by" in order to get an array that is

[<title>, <date>], 

where < date > is an optional entry.

So for example, if I have the sentence "get eggs by friday", it would be split into

[get eggs, friday].

However, if the title contains the word "by", it would be split as well, for example "chill by the beach by friday" gives

[chill, the beach, friday] 

which is not what i want.

Furthermore, because my date is optional, "chill by the beach" would give me

[chill, the beach]

I did think about splitting around the last "by" only, but this example proves that this wouldnt work because the last "by" is in the title.

I am currently using Java regex and the command String.split(...) for this. Is there anyway to get what I want or is this impossible without escaping the front "by"("chill \\by the beach by friday" then removing the "\\" after the split)?

Answer 1

The below regex would split the string into two only based on the delimiter by which exists at the last followed by exactly one word.

string.split("\\s+by\\s+(?=\\S+$)");

or

Include all the possible day's inside the lookahead.

string.split("\\s+by\\s+(?=(?:friday|monday|saturday)$)");