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Answer 11

Listings

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Answers

Answer 11

True.

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Answer 10

True. Every new class inherits a default version of the equals method from the class named Object. Therefore, a new class that implements the Comparator interface already has such a method. The new class is free to override the inherited version, or to simply make use of the inherited version.

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Answer 9

True.

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Answer 8

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 4, 3, 2, and 1 with no duplicates.

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Answer 7

False. In Listing 1 , the constructor that is called to instantiate a new TreeSet object receives an incoming parameter of type Comparator . Once again, don't confuse the two interfaces simply because they have similar names.

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Answer 6

False. It is possible to instantiate a new TreeSet object using a constructor that receives an incoming reference to a Comparator object, in which case it is not necessary for the objects in the collection to implementthe Comparable interface. Don't confuse the two interfaces.

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Answer 5

1234

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Answer 4

False. Although the name of the Comparable interface is similar to the name of the Comparator interface, they are different interfaces. Don't be confused by the similarity of the names.

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Answer 3

True.

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Answer 2

True.

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Answer 1

False. The sorting order established by a Comparator may be different or may be the same as the natural order.

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Complete program listing

Listing 1 . Comparator02.java.
//File Comparator02.java //Copyright 2001, R.G.Baldwinimport java.util.*; import java.io.Serializable;public class Comparator02{ public static void main(String args[]){ new Worker().doIt();}//end main() }//end class Comparator02class Worker{ public void doIt(){Iterator iter; Collection ref;ref = new TreeSet(new TheComparator()); Populator.fillIt(ref);iter = ref.iterator(); while(iter.hasNext()){System.out.print(iter.next()); }//end while loopSystem.out.println(); }//end doIt()}// end class Worker class Populator{public static void fillIt(Collection ref){ ref.add(new MyClass(4));ref.add(new MyClass(4)); ref.add(new MyClass(3));ref.add(new MyClass(2)); ref.add(new MyClass(1));}//end fillIt() }//end class Populatorclass MyClass{ int data;MyClass(){ data = 0;}//end noarg constructor MyClass(int data){this.data = data; }//end parameterized constructorpublic String toString(){ return "" + data;}//end overridden toString() }//end MyClassclass TheComparator implements Comparator,Serializable{public int compare(Object o1,Object o2){ if(!(o1 instanceof MyClass))throw new ClassCastException(); if(!(o2 instanceof MyClass))throw new ClassCastException(); if(((MyClass)o1).data<((MyClass)o2).data) return -1;if(((MyClass)o1).data>((MyClass)o2).data) return 1;else return 0; }//end compare()public boolean equals(Object o){ if(!(o instanceof TheComparator))return false; else return true;}//end overridden equals() }//end class TheComparator

Miscellaneous

This section contains a variety of miscellaneous information.

Housekeeping material
  • Module name: Java4090r: Review
  • File: Java4090r.htm
  • Published: 12/01/13
Disclaimers:

Financial : Although the Connexions site makes it possible for you to download aPDF file for this module at no charge, and also makes it possible for you to purchase a pre-printed version of the PDF file, youshould be aware that some of the HTML elements in this module may not translate well into PDF.

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Affiliation : I am a professor of Computer Information Technology at Austin Community College in Austin, TX.

-end-

Questions & Answers

hello, I am happy to help!
Shirley Reply
please can go further on polynomials quadratic
Abdullahi
I need quadratic equation link to Alpa Beta
Abdullahi Reply
find the value of 2x=32
Felix Reply
divide by 2 on each side of the equal sign to solve for x
corri
X=16
Michael
Want to review on complex number 1.What are complex number 2.How to solve complex number problems.
Beyan
use the y -intercept and slope to sketch the graph of the equation y=6x
Only Reply
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
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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
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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