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This module contains review questions and answers keyed to the module titled Java4090: The Comparator Interface, Part 1.

Revised: Wed Apr 06 23:12:11 CDT 2016

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Table of contents

Preface

This module is one in a collection of modules on Java Collections designed for teaching ITSE2321 - Object-Oriented Programming (Java) at Austin Community College in Austin, TX.

This module contains review questions and answers keyed to the module titled Java4090: The Comparator Interface, Part 1 .

Once you study that module, you should be able to answer the review questions in this module.

The questions and the answers in this module are connected by hyperlinks to make it easy for you to navigate from the question to the answer and back again.

Questions

Question 1 .

True or False? The sorting order established by a Comparator must be the same as the natural order.

Answer 1

Question 2

True or False? A Comparator can be used to establish a sorting order for objects that don't have a natural ordering.

Answer 2

Question 3

True or False? The use of a Comparator is an alternative to the implementation of the Comparable interface.

Answer 3

Question 4

True or False? Comparable and Comparator are two different names for the same interface.

Answer 4

Question 5

What output is produced by the program shown in Listing 1 ?

  • Compiler Error
  • Runtime Error
  • 44321
  • 4321
  • 1234
  • 12344

Answer 5

Question 6

True or False? It is possible to instantiate a new TreeSet object using a constructor that receives an incoming reference to a Comparable object, in which case it is not necessary for the objects in the collection to implementthe Comparator interface.

Answer 6

Question 7

True or False? In Listing 1 , the constructor that is called to instantiate a new TreeSet object receives an incoming parameter of type Comparable .

Answer 7

Question 8

True or False? When the fillIt method shown in Listing 1 returns, the collection object referred to by ref will contain references to five objects of type MyClass with those objects encapsulating the values 4, 4, 3, 2, and 1.

Answer 8

Question 9

True or False? When the fillIt method shown in Listing 1 returns, the collection object referred to by ref will contain references to four objects of type MyClass with those objects encapsulating the values 1, 2, 3, and 4 sorted into the order shown.

Answer 9

Question 10

True or False? Given: the Comparator interface declares the two methods listed below:

  • public int compare(Object o1, Object o2)
  • public boolean equals(Object obj)

(Note that the Java documentation would replace the type Object with the generic type T. However, generics are beyond the scope of this course.)

A class that implements the Comparator interface must provide a concrete definition for the compare method but providing a concrete definition for the equals method is optional.

Answer 10

Question 11

True or False? The general behavior of the compare method of a Comparator object compares its two arguments for order and returns a negative integer, zero, or a positiveinteger as the first argument is less than, equal to, or greater than the second.

Questions & Answers

how do we prove the quadratic formular
Seidu Reply
hello, if you have a question about Algebra 2. I may be able to help. I am an Algebra 2 Teacher
Shirley Reply
thank you help me with how to prove the quadratic equation
Seidu
may God blessed u for that. Please I want u to help me in sets.
Opoku
what is math number
Tric Reply
4
Trista
x-2y+3z=-3 2x-y+z=7 -x+3y-z=6
Sidiki Reply
Need help solving this problem (2/7)^-2
Simone Reply
x+2y-z=7
Sidiki
what is the coefficient of -4×
Mehri Reply
-1
Shedrak
the operation * is x * y =x + y/ 1+(x × y) show if the operation is commutative if x × y is not equal to -1
Alfred Reply
An investment account was opened with an initial deposit of $9,600 and earns 7.4% interest, compounded continuously. How much will the account be worth after 15 years?
Kala Reply
lim x to infinity e^1-e^-1/log(1+x)
given eccentricity and a point find the equiation
Moses Reply
12, 17, 22.... 25th term
Alexandra Reply
12, 17, 22.... 25th term
Akash
College algebra is really hard?
Shirleen Reply
Absolutely, for me. My problems with math started in First grade...involving a nun Sister Anastasia, bad vision, talking & getting expelled from Catholic school. When it comes to math I just can't focus and all I can hear is our family silverware banging and clanging on the pink Formica table.
Carole
I'm 13 and I understand it great
AJ
I am 1 year old but I can do it! 1+1=2 proof very hard for me though.
Atone
Not really they are just easy concepts which can be understood if you have great basics. I am 14 I understood them easily.
Vedant
hi vedant can u help me with some assignments
Solomon
find the 15th term of the geometric sequince whose first is 18 and last term of 387
Jerwin Reply
I know this work
salma
The given of f(x=x-2. then what is the value of this f(3) 5f(x+1)
virgelyn Reply
hmm well what is the answer
Abhi
If f(x) = x-2 then, f(3) when 5f(x+1) 5((3-2)+1) 5(1+1) 5(2) 10
Augustine
how do they get the third part x = (32)5/4
kinnecy Reply
make 5/4 into a mixed number, make that a decimal, and then multiply 32 by the decimal 5/4 turns out to be
AJ
how
Sheref
A soccer field is a rectangle 130 meters wide and 110 meters long. The coach asks players to run from one corner to the other corner diagonally across. What is that distance, to the nearest tenths place.
Kimberly Reply
Jeannette has $5 and $10 bills in her wallet. The number of fives is three more than six times the number of tens. Let t represent the number of tens. Write an expression for the number of fives.
August Reply
What is the expressiin for seven less than four times the number of nickels
Leonardo Reply
How do i figure this problem out.
how do you translate this in Algebraic Expressions
linda Reply
why surface tension is zero at critical temperature
Shanjida
I think if critical temperature denote high temperature then a liquid stats boils that time the water stats to evaporate so some moles of h2o to up and due to high temp the bonding break they have low density so it can be a reason
s.
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris Reply
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Source:  OpenStax, Object-oriented programming (oop) with java. OpenStax CNX. Jun 29, 2016 Download for free at https://legacy.cnx.org/content/col11441/1.201
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