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Answer 15

C. 1.0 2.0

Explanation 15

This is an upgrade of the program from Question 14 . This program applies the proper downcast operator to the references extracted from the array of type Object before attempting to call the method named getData on those references. (For more information, see the discussion of Question 14 .)

As a result of applying a proper downcast, the program compiles and runs successfully.

Back to Question 15

Answer 14

A. Compiler Error

Explanation 14

Storing references in a generic array of type Object

This program stores references to two objects instantiated from a new class named MyClass in the elements of an array object of declared type Object . That is OK.

Calling a method on the references

Then the program extracts the references to the two objects and attempts to call the method named getData on each of the references. That is not OK.

Downcast is required

Because the method named getData is not defined in the class named Object , in order to call this method on references extracted from an array of type Object , it is necessary to downcast the references to the class in which the method isdefined. In this case, the method is defined in the new class named MyClass (but it could be defined in an intermediate class in the class hierarchy if the newclass extended some class further down the hierarchy) .

Here is a partial listing of the compiler error produced by this program:

Ap062.java:15: error: cannot find symbol A[0].getData() + " " + ^symbol: method getData() location: class Object

Back to Question 14

Answer 13

D. None of the above.

Explanation 13

The array object of type Object in this program is capable of storing a reference to a new object instantiated from the new class named MyClass . However, because the new class does not override the toString method, when a string representation of the new object is displayed, the stringrepresentation is created using the version of the toString method that is inherited from the Object class. That causes this program to produce an output similar to the following:

Zero 1 MyClass@273d3c

Back to Question 13

Answer 12

C. Zero 1 2.0

Explanation 12

A type-generic array object

As explained in Question 11 , an array object of the type Object is a generic array that can be used to store references to objects instantiated from anyclass.

Storing mixed reference types

This program instantiates objects from the classes String , Integer , and Double , and stores those objects' references inthe elements of an array of type Object . Then the program accesses the references and uses them to display string representations of each of theobjects.

Polymorphic behavior applies

Once again, polymorphic behavior involving overridden versions of the toString method were involved and it was not necessary to downcast the references to their true type to display string representations of the objects.

Back to Question 12

Answer 11

C. Zero One Two

Explanation 11

Storing references to subclass types

When you create an array object for a type defined by a class definition, the elements of the array can be used to store references to objects of that classor any subclass of that class.

Questions & Answers

find the 15th term of the geometric sequince whose first is 18 and last term of 387
Jerwin Reply
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
how do they get the third part x = (32)5/4
kinnecy Reply
can someone help me with some logarithmic and exponential equations.
Jeffrey Reply
sure. what is your question?
okay, so you have 6 raised to the power of 2. what is that part of your answer
I don't understand what the A with approx sign and the boxed x mean
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
I'm not sure why it wrote it the other way
I got X =-6
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
oops. ignore that.
so you not have an equal sign anywhere in the original equation?
is it a question of log
Commplementary angles
Idrissa Reply
im all ears I need to learn
right! what he said ⤴⤴⤴
what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
Kevin Reply
a perfect square v²+2v+_
Dearan Reply
kkk nice
Abdirahman Reply
algebra 2 Inequalities:If equation 2 = 0 it is an open set?
Kim Reply
or infinite solutions?
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Embra Reply
if |A| not equal to 0 and order of A is n prove that adj (adj A = |A|
Nancy Reply
rolling four fair dice and getting an even number an all four dice
ramon Reply
Kristine 2*2*2=8
Bridget Reply
Differences Between Laspeyres and Paasche Indices
Emedobi Reply
No. 7x -4y is simplified from 4x + (3y + 3x) -7y
Mary Reply
how do you translate this in Algebraic Expressions
linda Reply
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
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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