Chapter 7 ■ String Processing

Answer: B. “b\D\w*@\w+\.com\b”

(“\b” is used to mark word boundaries, “\D” is used to match any non-digit number, and “\w*” is used to match any word of length zero or more. The remaining part is similar to that used earlier.)

6.What kind of strings will the regex "\d*[02468]" match?

A.Any number containing at least one of the 0, 2, 4, 6, or 8 digits.

B.Any number starting from one of the 0, 2, 4, 6, or 8 digits.

C.Any number containing all the specified (0, 2, 4, 6, 8) digits at the end of the number.

D.Any number ending with one of the specified (0, 2, 4, 6, 8) digits.

Answer: D. Any number ending with one of the specified (0, 2, 4, 6, 8) digits. (All even numbers.)

Summary

Searching, Parsing, and Building Strings

•You can use the overloaded versions of the method indexOf() in the String class for forward searching in a string, lastIndexOf() for backward searching a string, and regionMatches() for comparing a “region” of text within a string.

•To convert from a primitive type value to String type object, you can make use of the overloaded valueOf() method, which takes a primitive type value as an argument and returns the String object. To convert from the String type object to a primitive type value, you can make use of the parse methods available for primitive types in the corresponding wrapper types of the primitive types.

•For parsing a string, you can use the split() method available in the String class. It takes a delimiter as an argument, and this argument is a regular expression.

Regular Expressions

•A regular expression defines a search pattern that can be used to execute operations such as string search and string manipulation.

•Use the Pattern and Matcher classes whenever you are performing search or replace on strings heavily; they are more efficient and faster than any other way to perform search/replace in Java.

•You can form groups within a regex. These groups can be used to specify quantifiers on a desired subset of the whole regex. These groups can also be used to specify back reference.

String Formatting

•The method printf() (and the method format() in the String class) uses string formatting flags to format strings.

•Each format specifier starts with the % sign; followed by flags, width, and precision information; and ending with a data type specifier. In this string, the flags, width, and precision information are optional but the % sign and data type specifier are mandatory.

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