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Learn through experimentation

I placed a print statement in each of the overloaded methods to display the type of that method's argument on the screen when the method is called. Byexamining the output, we can see that the method with the float parameter was called first (corresponding to the parameter of type int ). Then the method with the double parameter was called (corresponding to the parameter of type double ).

Converted int to float

Thus, the system selected the overloaded method requiring an incoming parameter of type float when the method was called passing an int as a parameter. The value of type int was automatically converted to type float .

In this case, it wasn't too important which method was called to process the parameter of type int , because the two methods do essentially the same thing -- compute and return the square of the incoming value.

However, if the behavior of the two methods were different from one another, it could make a lot of difference, which one gets called on an assignmentcompatible basis. (Even in this case, it makes some difference. As we will see later, when a very large int value is converted to a float , there is some loss in accuracy. However, when the same very large int value is converted to a double , there is no loss in accuracy.)

Avoiding the problem

One way to avoid this kind of subtle issue is to avoid passing assignment-compatible values to overloaded methods.

Passing assignment-compatible values to overloaded methods allows the system to resolve the issue through automatic type conversion. Automatic typeconversion doesn't always provide the best choice.

Using a cast to force your choice of method

Usually, you can cast the parameter values to a specific type before calling the method and force the system to select your overloaded method of choice.

For example, in this problem, you could force the method with the double parameter to handle the parameter of type int by using the following cast when the method named square is called:

square((double)x)

However, as we will see later, casting may not be the solution in every case.

Back to Question 2

Answer 1

C. 9 17.64

Explanation 1

What is method overloading?

A rigorous definition of method overloading is very involved and won't be presented here. However, from a practical viewpoint, a method is overloaded whentwo or more methods having the same name and different formal argument lists are defined in the class from which an object is instantiated, or are inherited intoan object by way of superclasses of that class.

How does the compiler select among overloaded methods?

The exact manner in which the system determines which method to call in each particular case is also very involved. Basically, the system determineswhich of the overloaded methods to execute by matching the types of parameters passed to the method to the types of arguments defined in the formal argumentlist.

Assignment compatible matching

However, there are a number of subtle issues that arise, particularly when there isn't an exact match. In selecting the version of the method to call,Java supports the concept of an "assignment compatible" match (or possibly more than one assignment compatible match) .

Briefly, assignment compatibility means that it would be allowable to assign a value of the type that is passed as a parameter to a variable whose typematches the specified argument in the formal argument list.

Selecting the best match

According to Java Language Reference by Mark Grand,

"If more than one method is compatible with the given arguments, the method that most closely matches thegiven parameters is selected. If the compiler cannot select one of the methods as a better match than the others, the method selection process fails and thecompiler issues an error message."

Understanding subtleties

If you plan to be a Java programmer, you must have some understanding of the subtle issues involving overloaded methods, and therelationship between overloaded methods and overridden methods. Therefore, the programs in this module will provide some of that information and discuss someof the subtle issues that arise.

Even if you don't care about the subtle issues regarding method overloading, many of those issues really involve automatic typeconversion. You should study these questions to learn about the problems associated with automatic type conversion.

This program is straightforward

However, there isn't anything subtle about the program for Question 1 . This program defines two overloaded methods named square . One requires a single incoming parameter of type int . The other requires a single incoming parameter of type double . Each method calculates and returns the square of the incoming parameter.

The program calls a method named square twice in succession, and displays the values returned by those two invocations. In the first case, an int value is passed as a parameter. This causes the method with the formal argument list oftype int to be called.

In the second case, a double value is passed as a parameter. This causes the method with the formal argument list of type double to be called.

Overloaded methods may have different return types

Note in particular that the overloaded methods have different return types. One method returns its value as type int and the other returns its value as type double . This is reflected in the output format for the two return vales as shown below:

9 17.64

Back to Question 1

-end-

Questions & Answers

do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
Daniel
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Maciej
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Abigail
Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
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Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
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Cied
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
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Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
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AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
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AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
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
Azam
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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
Azam
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Prasenjit
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Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit 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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