Create a class ConstructorTest with a constructor
that takes no arguments and prints a message like "Object constructed".
Create an object of this class.
Overload the constructor in the class ConstructorTest
with a new constructor which takes a String argument and prints it along with
the message from Exercise 1.
Create a two dimensional array myValues of
int values and a two dimensional array myObjects
of Objects of class Integer. Both arrays should be of the following dimensions:
The outer array has three fields. The first inner array has two fields, the
second inner array has four fields, and the third inner array has two fields.Compare
the creation of te two arrays. Print out the array content of one of the arrays
that reflects the array structure.
Create a class Counter with an adequate data
member. Write four methods, one to get the value of the counter (getValue),
one to increment the counter (increment), one
to decrement the counter (decrement), and one
to reset the counter to zero (reset). Make sure
that the value of the counter never gets less than zero.
Create an object of your class Counter and
assign it to two different variables. Change the state of the object, calling
your method on one variable. See what happens if you call the getValue-method
on the other variable.
Define a class Fraction that represents mathematical
fractions like 1/4 or 3/2. Provide data members for the numerator and the
denominator. Make sure they are only accessible via methods and that the denominator
is not zero. Define a constructor that takes two values of type
int and creates a fraction and a method for each of the following purposes
return the denominator (getDenominator)
return the numerator (getNumerator)
add two fractions and return the result fraction (plus)
multiply two fractions and return the result fraction (multiplyWith)
divide a fraction by another fraction and return the result fraction (divideBy)
subtract a fraction from another fraction and return the result fraction
(minus)
test the equality of two fractions (equals,
see Lecture)
Test your class Fraction. Insert a method printFraction for this purpose.
* Canceling down fractions, the fraction 4/8 is equal to 1/2. Work over
your class Fraction again taking this fact into account. Change at least the
implementation of equals. Use the class Sieve for canceling down the
fractions. (Hint: Search for prime numbers that are divisors of the denominator
as well as of the numerator and divide both parts by this primes.) Alternatively
you may also use a "greatest common divisor" Algorithm for
this purpose.
The exercises marked with a star (*) are intended as additional opportunities to train
your Java knowledge.
