Objects and classes - Data Structures and Problem Solving Using Java - page 104

Modify the BigRational class so that 0/0 is legal and is interpreted as
“Indeterminate” by toString .

3.23

Write a program that reads a data file containing rational numbers,
one per line, stores the numbers in an ArrayList , removes any dupli-
cates, and then outputs the sum, arithmetic mean, and harmonic mean
of the remaining unique rational numbers.

3.24

Suppose you would like to print a two dimensional array in which all
numbers are between 0 and 999. The normal way of outputting each
number might leave the array misaligned. For instance:
54 4 12 366 512
756 192 18 27 4
14 18 99 300 18
Examine the documentation for the format method in the String class
and write a routine that outputs the two-dimensional array in a nicer
format, such as
54 4 12 366 512
756 192 18 27 4
14 18 99 300 18

3.25

Package java.math contains a class BigDecimal , used to represent an
arbitrary-precision decimal number. Read the documentation for
BigDecimal and answer the following questions:
a.

3.26

Is BigDecimal an immutable class?

b. If bd1.equals(bd2) is true, what is bd1.compareTo(bd2) ?

c. If bd1.compareTo(bd2) is 0, when is bd1.equals(bd2) false?

d. If bd1 represents 1.0 and bd2 represents 5.0, by default what is

bd1.divide(bd2) ?

e. If bd1 represents 1.0 and bd2 represents 3.0, by default what is

bd1.divide(bd2) ?

f. What is MathContext.DECIMAL128 ?

g. Modify the BigRational class to store a MathContext that can be

initialized from an additional BigRational constructor (or which
defaults to MathContext.UNLIMITED ). Then add a toBigDecimal
method to the BigRational class.

An Account class stores a current balance, and provides getBalance ,
deposit , withdraw , and toString methods in addition to at least one
constructor. Write and test an Account class. Make sure your withdraw
method throws an exception if appropriate.

3.27