Questions
- What are the three public classes in the
java.util.regex
package? Describe the purpose of each.- Consider the string literal
"foo"
. What is the start index? What is the end index? Explain what these numbers mean.- What is the difference between an ordinary character and a metacharacter? Give an example of each.
- How do you force a metacharacter to act like an ordinary character?
- What do you call a set of characters enclosed in square brackets? What is it for?
- Here are three predefined character classes:
\d
,\s
, and\w
. Describe each one, and rewrite it using square brackets.- For each of
\d
,\s
, and\w
, write two simple expressions that match the opposite set of characters.- Consider the regular expression
(dog){3}
. Identify the two subexpressions. What string does the expression match?
Exercises
- Use a backreference to write an expression that will match a person's name only if that person's first name and last name are the same.