add character to a string at specific place based on Regular expression

Question

Is there a way to add a character, say '\t', at specific position of the string?

For example:

String str = "key1=123 key2=text with spaces key3=foo";

I need to replace all spaces before keys with tabs in the key value pair string.

Note that some values may contain spaces.

I tried to split the KV pair based in space but I couldn't as there are space in some of the values. not familiar with the REGEX can you help. — Mohan M
– Mohan M, Commented Jan 5, 2017 at 11:56
Your question is pretty unclear. It sounds like you don't actually know the specific position (that would suggest you know the index already). Instead, it's defined in terms of "every key position" - which you haven't clearly defined. Can your values include = signs? — Jon Skeet
– Jon Skeet, Commented Jan 5, 2017 at 12:00
Most probably you will be succeeded with String.replaceAll() method — lospejos
– lospejos, Commented Jan 5, 2017 at 12:09

Bohemian · Accepted Answer · 2017-01-05 12:26:26Z

1

Use a look ahead:

str = str.replaceAll(" (?=\\w+=)", "\t");

or similar, capture the key and put it back:

str = str.replaceAll(" (\\w+=)", "\t$1");

answered Jan 5, 2017 at 12:26

Bohemian♦

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1 Comment

Thanks, that really helped.