Consider a set of strings like the following: Memory size = 4,194,304 KB Cache

Question

Asked: June 18, 20262026-06-18T03:31:58+00:00 2026-06-18T03:31:58+00:00

Consider a set of strings like the following:

Memory size = 4,194,304 KB
Cache size=   32,768 K
Number of cores = 8
Note   =4,000,000 KB is less than 4 GB

Is there a generic and not too complex Java regular expression that matches each string entirely and produces the following groups?

"Memory size", "4,194,304", "KB"
"Cache size", "32,768", "K"
"Number of cores", "8"
"Note", "4,000,000 KB is less than 4 GB"

These groups are key, value and (optional) suffix.

Additional requirements:

The value (i.e., the part after ‘=’) is not necessarily a number
Any spaces on either side of ‘:’ should be removed in one pass, without backtracking
The “KB” and “K” string matching is not case sensitive
The captured groups should always have the same index (ideally, 3 groups for key/value/suffix, with the same group index for all matches)

Clearly, a simple expression like

does not fully cover the specification above.

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Editorial Team · Answer 1 · 2026-06-18T03:31:59+00:00

Editorial Team

A regex that fully covers the spec above is:

^([^=]+?) *= *(.+?) *$

EDIT

Turns out I missed the K/KB part. Here is the amended version:

^([^=]+?) *= *(.+?) *(KB?)? *$

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