Java 9 Regular Expressions

Greedy versus reluctant (lazy) matching using quantifiers

So far, we have discussed all the quantifiers available to us in a regular expression to match fixed-size or variable-length text. These quantifiers are, by default, greedy in nature. Greediness is in terms of their matching. In a regex, quantifiers attempt to match the longest possible text, from left to right. Only when the regex engine fails to complete a match, it moves back in the input text one character at a time, as required, to complete the match. Sometimes, the regex engine moves back and forth multiple times in attempts to complete a match in a complex (nested) regular expression.

So, for example, if the input is pqrstmprt and our regular expression is p.+r, then our match ...