Conditionals and Loops - Java Software Solutions: Foundations of Program Design - page 229

To determine the relative ordering of two strings, use the compareTo method
of the String class. The compareTo method is more versatile than the equals
method. Instead of returning a boolean value, the compareTo method returns
an integer. The return value is negative if the String object through which the
method is invoked precedes (is less than) the string that is passed in as a param-
eter. The return value is zero if the two strings contain the same characters.
The return value is positive if the String object through which the method is
invoked follows (is greater than) the string that is passed in as a parameter. For
example:
int result = name1.compareTo(name2);
if (result < 0)
System.out.println (name1 + " comes before " + name2);
else
if (result == 0)
System.out.println ("The names are equal.");
else
System.out.println (name1 + " follows " + name2);
Keep in mind that comparing characters and strings is based on the Unicode
character set (see Appendix C). This is called a lexicographic ordering . If all alpha-
betic characters are in the same case (upper or lower), the lexicographic ordering
will be alphabetic ordering as well. However, when comparing two strings, such
as "able" and "Baker" , the compareTo method will conclude that "Baker" comes
first because all of the uppercase letters come before all of the lowercase letters
in the Unicode character set. A string that is the prefix of another, longer string
is considered to precede the longer string. For example, when comparing the
two strings "horse" and "horsefly" , the compareTo method will conclude that
"horse" comes first.
SELF-REVIEW QUESTIONS (see answers in Appendix N)
SR 5.13 Why must we be careful when comparing floating point values for
equality?
SR 5.14 How do we compare strings for equality?
SR 5.15 Write an equals method for the Die class of Section 4.2. The method
should return true if the Die object it is invoked on has the same
facevalue as the Die object passed as a parameter, otherwise it should
return false .
SR 5.16 Assume the String variables s1 and s2 have been initialized. Write an
expression that prints out the two strings on separate lines in lexico-
graphic order.