Using JAVA:

CS1400 Fall 2017

Instructions: You may rework the following problems for 1/2 credit on

each. You must get the problem completely correct for additional credit.

Extra credit will be given on a per question basis.

Problems that can be worked: (4, 11, 12, 13, 14, 17, 21, 24, 25, 26, 27,

28, 30, 31)

4. Assume you are in the main method in a MouseDriver class.

a) Write a statement that creates a Mouse object to represent your

personal pet mouse, whom you called "Sweetie".

b) Write another statement that uses a getWeight method (defined in the

Mouse class) to retrieve Sweetie's current weight, and then assign

that retrieved value to a previously declared local variable called

weight.

11. Assume a Car class includes an equals method, whose heading looks like

this:

public boolean equals(Car car)

a) Write a Java expression that uses this method to compare two Car

objects, car1 and car2.

b) Assuming the Car class defines just two instance variables, make and

model, write Java code that implements this equals method.

12. Suppose a CarDriver program has already created and fully initialized

an instance called car1 of a class Car, which defines two private instance

variables, make and model. Then suppose CarDriver creates a copy of this

car with these two statements:

Car car2 = new Car();

car1.copyTo(car2);

Write Java code to implement this copyTo method.

13. Assume you have a Car class that declares two private instance

variables, make and model.

Write Java code that implements a two-parameter constructor that

instantiates a Car object and initializes both of its instance variables.

14. Assume a Car class already has a two-parameter constructor that

initializes make and model attributes. Write Java code that implements an

additional constructor that has three parameters - two String parameters

to initialize the same make and model attributes initialized by the two-

parameter constructor, plus another int parameter to initialize a miles

variable. Your code should utilize the two-parameter constructor to

implement those operations which the two-parameter constructor is already

able to perform.

17. Assume that a class called Cat includes a method with this header:

public static int getCatCount()

Write a Java statement that retrieves the current cat count and assigns it

to an already-declared local variable called catCount in the main method

of the CatDriver class.

21. Write a single statement that copies all the elements in

char[] arr1 = {'x','y','z'};

to the last elements of

char[] arr2 = new char[26];

24. Write a Java statement that declares an array of char elements called

vowels and initializes it with

a

,

e

,

i

,

o

, and

u

.

25. Assume code that has imported Scanner and instantiated it for keyboard

input as stdIn. Write a code fragment that does the following:

a) Declares but does not initialize roots to be an array of doubles.

b) Prompts the user to enter the number of elements and then initializes

roots with an array object whose length equals the input.

c) Uses a for loop to fill each array element with the square root of

that element's index value.

27. Suppose you want a Java program to represent this table of int values:

16 -3 11

27 49 -7

a) Write a single Java statement that declares a two-dimensional array

of int's called numberTable and initializes it so that its element

values correspond to the above table.

b) Write a Java code fragment that prints the values in the numberTable

array as they appear above, where each number in a given row is

preceded by a tab. But make your for loop upper limits able to

accommodate an arbitrary number of rows and an arbitrary number of

columns in each row.

28. Assume the existence of a class called Student which defines two

instance variables:

private String name;

private char gender; // 'M' for male or 'F' for female

Assume this class implements these two methods:

public char getGender()

public String toString() // name and gender

Given an array of Student elements called students, write a for-each loop

that searches the array for male students only and prints each male

student's information on a separate line. Allow for the possibility that

some of the elements in the array may be null.

30. Write a Java statement that removes the Student element currently at

index position i in an ArrayList called students.

31. Write the names of three methods implemented by both ArrayList and

LinkedList classes. [Hint: both of these classes implement the List

interface, which specifies 25 distinct methods.]