Search for a word in a String

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If I am looking for a particular word inside a string, for example, in the string “how are you” I am looking for “are”. Would a regular indexOf() work faster and better or a Regex match()

String testStr = "how are you";
String lookUp = "are";

if (testStr.indexOf(lookUp) != -1)

if (testStr.match(".*"+lookUp+".*"))

Which of the two methods above is a better way of looking for a string inside another string? Or is there a much better alternative?

  • Ivard


If you don’t care whether it’s actually the entire word you’re matching, then indexOf() will be a lot faster.

If, on the other hand, you need to be able to differentiate between are, harebrained, aren't etc., then you need a regex: bareb will only match are as an entire word (\bare\b in Java).

b is a word boundary anchor, and it matches the empty space between an alphanumeric character (letter, digit, or underscore) and a non-alphanumeric character.

Caveat: This also means that if your search term isn’t actually a word (let’s say you’re looking for ###), then these word boundary anchors will only match in a string like aaa###zzz, but not in +++###+++.

Further caveat: Java has by default a limited worldview on what constitutes an alphanumeric character. Only ASCII letters/digits (plus the underscore) count here, so word boundary anchors will fail on words like élève, relevé or ärgern. Read more about this (and how to solve this problem) here.

Source: stackoverflow