<< Chapter < Page Chapter >> Page >

The statement containing the cast operator is shown below for convenient viewing.

myIntVar = (int)myDoubleVar;

Syntax of a cast operator

The cast operator consists of the name of a type contained within a pair of matching parentheses.

A unary operator

The cast operator always appears to the left of an expression whose type is being converted to the type specified by the cast operator.

Assuming responsibility for potential problems

When dealing with primitive types, the cast operator is used to notify the compiler that the programmer is willing to assume the risk of a possible loss ofprecision in a narrowing conversion.

No loss of precision here

In this case, there was no loss in precision, but that was only because the value stored in the double variable was within the allowable value range for an int .

In fact, it was the largest positive value that can be stored in the type int . Had it been any larger, a loss of precision would have occurred.

More on this later ...

I will have quite a bit more to say about the cast operator in future modules. I will also have more to say about the use of the assignmentoperator in conjunction with the non-primitive types.

Back to Question 4

Answer 3

A. Compiler Error

Explanation 3

Conversion from double to int is not automatic

This program attempts to assign a value of type double to a variable of type int .

Even though we know that the specific double value involved would fit in the int variable with no loss of precision, the conversion from double to int is not a widening conversion.

This is a narrowing conversion

In fact, it is a narrowing conversion because the allowable value range for an int is less than the allowable value range for a double .

The conversion is not allowed by the compiler. The following compiler error occurs under JDK 1.3:

Ap012.java:16: possible loss of precision found : doublerequired: int myIntVar = myDoubleVar myIntVar = myDoubleVar;

Back to Question 3

Answer 2

C. 2.147483647E9

Explanation 2

Declare a double

The method named doAsg first declares a local variable of type double named myDoubleVar without providing an initial value.

Declare and initialize an int

Then it declares an int variable named myIntVar and initializes its value to the integer value 2147483647 (you learned about Integer.MAX_VALUE in an earlier module) .

Assign the int to the double

Following this, the method assigns contents of the int variable to the double variable.

An assignment compatible conversion

This is an assignment compatible conversion. In particular, the integer value of 2147483647 is automatically converted to a double value and stored in the double variable.

The double representation of that value is what appears on the screen later when the value of myDoubleVar is displayed.

What is an assignment compatible conversion?

An assignment compatible conversion for the primitive types occurs when the required conversion is a widening conversion.

What is a widening conversion?

A widening conversion occurs when the allowable value range of the type of the left operand of the assignment operator is greater than the allowable valuerange of the right operand of the assignment operator.

Questions & Answers

what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
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
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
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
Abhijith Reply
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
On having this app for quite a bit time, Haven't realised there's a chat room in it.
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
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
how to synthesize TiO2 nanoparticles by chemical methods
Zubear
what's the program
Jordan
?
Jordan
what chemical
Jordan
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Good
Got questions? Join the online conversation and get instant answers!
QuizOver.com Reply

Get the best Algebra and trigonometry course in your pocket!





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
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Object-oriented programming (oop) with java' conversation and receive update notifications?

Ask