Espresso: A Concentrated Introduction to Java
Summary: In this laboratory, you will explore some of the standard methods by adding them to existing classes.
Primary Classes Used:
Source Files:
Contents
In this lab, you will continue to use the Code project
and the username.fractions
package.
a. As always, start Eclipse.
b. If you've configured Fraction
so that it automatically
simplifies fractions when they are constructed, remove the code to do
so.
a. In your main class, create a Fraction
of your
choice and print it out. What happens?
b. The Fraction
class comes with a toString
method. Remove it.
c. Run your main class again. What happens? You've now seen the default
toString
method.
d. Reinsert the toString
method.
a. In your main class, create the fractions fourThirds
and oneThird
with the natural value for each. For
example,
Fraction fourThirds = new Fraction(4,3); Fraction oneThird = new Fraction(1,3);
b. Determine whether or not the fractional portion of fourThirds
is the same as oneThird
. For example,
if (fourThirds.fractional().equals(oneThird)) { pen.println("The fractional portion of " + fourThirds + " equals " + oneThird); } else { pen.println("The fractional portion of " + fourThirds + " does not equal " + oneThird); }
c. Write an equals
method that indicates that two
fractions are equal if their numerators are the same and their
denominators are the same.
d. Verify that the code from step b now indicates that the two fractions are equal.
a. Extend your main class to create two fractions, oneHalf
and one
, with the obvious values.
b. Write code that determines whether oneHalf.add(oneHalf)
is equal to one
. (Hint: If you followed instructions above,
it should not be.)
c. Fix the equals
method so that it considers the two
equal. Note that you may not use gcd
or
simplify
in determining equality.
d. Test your change using the code from step b.
a. Write a compareTo(Fraction other)
method for your
Fraction
class.
b. Test your compareTo
method with each of the following pairs
oneHalf.add(oneHalf)
and one
c. Correct your method if you identified any errors above.
Write and test a hashCode
method for the
Fraction
class.
Write and test the clone
method for the
Fraction
class.
Wednesday, 22 February 2006 [Samuel A. Rebelsky]
Sunday, 26 February 2006 [Samuel A. Rebelsky]
Monday, 27 February 2006 [Samuel A. Rebelsky]
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