Wildcard Character
A regular expression can be made up of ordinary characters, which are upper and lowercase letters and digits, plus sequences of metacharacters (A metacharacter is a character that has a special meaning to a computer program). The pattern in the previous program was just the word “java”, but what if you wanted to search a string for occurrences of “age” or “axe” or “ace” or even any three-letter word beginning with “a” and ending with “e” ?
You can deal with any of these possibilities with regular expressions. One option is to specify the middle character as a wildcard (a wildcard is a symbol used to replace or represent characters) by using a period; a period is one example of a meta-character. This meta-character matches any character except end-of-line, so the regular expression “a.e”, represents any sequence of three characters that starts with “a” and ends with “e”.
Program
Example 2
Program Source
import java.util.regex.Pattern; import java.util.regex.Matcher; public class Javaapp { public static void main(String[] args) { Pattern pat = Pattern.compile("a.e"); Matcher mat = pat.matcher("ageeyaxeggacezate1are"); int i = 0; while(mat.find()) { i++; System.out.println(i+"th subsequence : "+mat.group()); } } }
Program Source
import java.util.regex.Pattern; import java.util.regex.Matcher; public class Javaapp { public static void main(String[] args) { Pattern pat = Pattern.compile("."); Matcher mat = pat.matcher("ABCDEFG"); int i = 0; while(mat.find()) { i++; System.out.println(i+"th subsequence : "+mat.group()); } } }