Regular expressions simplify pattern-matching code - 19

The code fragment above specifies a regex that matches a comma character immediately followed by a single-space character and produces the following output:

John Doe

47

Hillsboro Road

32000

Note

String incorporates three convenience methods that invoke their equivalent Pattern methods: public boolean matches(String regex), public String [] split(String regex), and public String [] split(String regex, int limit).

Matcher methods

Matcher objects support different kinds of pattern match operations, such as scanning text for the next match; attempting to match the entire text against a pattern; and attempting to match a portion of text against a pattern. Accomplish those match operations with the following methods:

• public boolean find(): scans text for the next match. That method either starts its scan at the beginning of the text or, if a previous invocation of the method returned true and the matcher has not been reset, at the first character following the previous match. A Boolean true value returns if a match is found. Listing 1 presents an example.
• public boolean find(int start): resets the matcher and scans text for the next match. The scan begins at the index specified by start. A Boolean true value returns if a match is found. Example: m.find (1); scans text beginning at index 1. (Index 0 is ignored.) If start contains a negative value or a value exceeding the length of the matcher's text, this method throws an IndexOutOfBoundsException object.
• public boolean matches(): attempts to match the entire text against the pattern. That method returns a Boolean true value if the entire text matches. Example: Pattern p = Pattern.compile ("\\w*"); Matcher m = p.matcher ("abc!"); System.out.println (p.matches ()); outputs false because the entire abc! text lacks word characters.
• public boolean lookingAt(): attempts to match the text against the pattern. That method returns a Boolean true value if the text matches. Unlike matches(), the entire text does not need to be matched. Example: Pattern p = Pattern.compile ("\\w*"); Matcher m = p.matcher ("abc!"); System.out.println (p.lookingAt ()); outputs true because the beginning of the abc! text consists of word characters only.