OBJECT-ORIENTED THINKING - Introduction to Java Programming: Comprehensive Version - page 399

3.

Java can automatically convert a primitive type value to its corresponding wrapper
object in the context and vice versa.

4.

The BigInteger class is useful for computing and processing integers of any size. The
BigDecimal class can be used to compute and process floating-point numbers with any
arbitrary precision.

5.

A String object is immutable; its contents cannot be changed. To improve efficiency
and save memory, the JVM stores two literal strings that have the same character
sequence in a unique object. This unique object is called an interned string object .

6.

A regular expression (abbreviated regex ) is a string that describes a pattern for match-
ing a set of strings. You can match, replace, or split a string by specifying a pattern.

7.

The StringBuilder and StringBuffer classes can be used to replace the String
class. The String object is immutable, but you can add, insert, or append new contents
into StringBuilder and StringBuffer objects. Use String if the string contents
do not require any change, and use StringBuilder or StringBuffer if they might
change.

Q UIZ

Answer the quiz for this chapter online at www.cs.armstrong.edu/liang/intro10e/quiz.html .

P ROGRAMMING E XERCISES

Sections 10.2-10.3
*10.1 ( The Time class ) Design a class named Time . The class contains:

The data fields hour , minute , and second that represent a time.

■

A no-arg constructor that creates a Time object for the current time. (The
values of the data fields will represent the current time.)

■

A constructor that constructs a Time object with a specified elapsed time
since midnight, January 1, 1970, in milliseconds. (The values of the data
fields will represent this time.)

■

A constructor that constructs a Time object with the specified hour, minute,
and second.

■

Three getter methods for the data fields hour , minute , and second ,
respectively.

■

A method named setTime(long elapseTime) that sets a new time
for the object using the elapsed time. For example, if the elapsed time is
555550000 milliseconds, the hour is 10 , the minute is 19 , and the second is
10 .
Draw the UML diagram for the class and then implement the class. Write
a test program that creates two Time objects (using new Time() and new
Time(555550000) ) and displays their hour, minute, and second in the format
hour:minute:second.
( Hint : The first two constructors will extract the hour, minute, and second
from the elapsed time. For the no-arg constructor, the current time can be
obtained using System.currentTimeMillis() , as shown in Listing 2.7,
ShowCurrentTime.java.)

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