The matchAll() function is used to apply a regular expression to a piece of text, and return a list of matching groups (elements found inside parentheses) as a two-dimensional String array. No matches will return null. If no groups are specified in the regexp, but the sequence matches, a two dimensional array is still returned, but the second dimension is only of length one.

To use the function, first check to see if the result is null. If the result is null, then the sequence did not match at all. If the sequence did match, a 2D array is returned. If there are groups (specified by sets of parentheses) in the regexp, then the contents of each will be returned in the array. Assuming, a loop with counter variable i, element [i][0] of a regexp match returns the entire matching string, and the match groups start at element [i][1] (the first group is [i][1], the second [i][2], and so on).

The syntax can be found in the reference for Java's Pattern class. For regular expression syntax, read the Java Tutorial on the topic.

matchAll(str,regexp)