Java Reference
In-Depth Information
Java SE 8
As you'll see in Section 17.7, you can combine regular-expression processing with Java SE
8 lambdas and streams to implement powerful String -and-file processing applications.
14.8 Wrap-Up
In this chapter, you learned about more String methods for selecting portions of String s
and manipulating String s. You learned about the Character class and some of the meth-
ods it declares to handle char s. The chapter also discussed the capabilities of the String-
Builder class for creating String s. The end of the chapter discussed regular expressions,
which provide a powerful capability to search and match portions of String s that fit a par-
ticular pattern. In the next chapter, you'll learn about file processing, including how per-
sistent data is stored and and retrieved.
Summary
Section 14.2 Fundamentals of Characters and Strings
• A character literal's value (p. 597) is its integer value in Unicode (p. 597). Strings can include
letters, digits and special characters such as + , - , * , / and $ . A string in Java is an object of class
String . String literals (p. 597) are often referred to as String objects and are written in a pro-
gram in double quotes.
Section 14.3 Class String
String objects are immutable (p. 599)—after they're created, their character contents cannot be
changed.
String method length (p. 599) returns the number of characters in a String .
String method charAt (p. 599) returns the character at a specific position.
String method regionMatches (p. 601) compares portions of two strings for equality.
String method equals tests for equality. The method returns true if the contents of the String s
are equal, false otherwise. Method equals uses a lexicographical comparison (p. 602) for String s.
• When primitive-type values are compared with == , the result is true if both values are identical.
When references are compared with == , the result is true if both refer to the same object.
• Java treats all string literals with the same contents as a single String object.
String method equalsIgnoreCase performs a case-insensitive string comparison.
String method compareTo uses a lexicographical comparison and returns 0 if the Strings are
equal, a negative number if the string that calls compareTo is less than the argument String and
a positive number if the string that calls compareTo is greater than than the argument String .
String methods startsWith and endsWith (p. 604) determine whether a string starts with or
ends with the specified characters, respectively.
String method indexOf (p. 605) locates the first occurrence of a character or a substring in a
string. String method lastIndexOf (p. 605) locates the last occurrence of a character or a sub-
string in a string.
String method substring copies and returns part of an existing string object.
String method concat (p. 608) concatenates two string objects and returns a new string object.
 
 
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