A regular expression is a special sequence of characters that helps in matching or finding other strings or sets of strings, using a specialized syntax held in a pattern. Java has support for regular expression usage through the
java.util.regex package. This topic is to introduce and help developers understand more with examples on how Regular Expressions must be used in Java.
You will need to add the following imports before you can use Regex:
import java.util.regex.Matcher import java.util.regex.Pattern
In java, a backslash is escaped with a double backslash, so a backslash in the regex string should be inputted as a double backslash. If you need to escape a double backslash (to match a single backslash with the regex, you need to input it as a quadruple backslash.
|Match the preceding character or subexpression 0 or more times|
|Match the preceding character or subexpression 1 or more times|
|Match the preceding character or subexpression 0 or 1 times|
The regex topic contains more information about regular expressions.