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Would require reconstructing the array object

Therefore, to convert an array object containing int values to an array object containing double values would require reconstructing the array object and allocating twice as much storage space foreach element in the array.

Restriction doesn't apply to arrays of references

As you have seen from previous questions, such a casting restriction does not apply to arrays containing references to objects. This may be because the amountof storage required to store a reference to an object is the same, regardless of the type of the object. Therefore, the allowable casts that you have seen in theprevious questions did not require any change to the size of the array. All that changed was some supplemental information regarding the type of objects to whichthe elements in the array refer.

Back to Question 11

Answer 10

C. 1.0 2.0

Explanation 10

Assigning array reference to variable of type Object

A reference to an array can be assigned to a non-array reference of the class named Object , as in the following statement extracted from the program, where A is a reference to an array object of type double .

Object B = A;

Note that there are no square brackets anywhere in the above statement. Thus, the reference to the array object is not being assigned to an array reference ofthe type Object[] . Rather, it is being assigned to an ordinary reference variable of the type Object .

Downcasting to an array type

Once the array reference has been assigned to the ordinary reference variable of the type Object , that reference variable can be downcast and used to access the individual elements in the array as illustrated in thefollowing fragment. Note the empty square brackets in the syntax of the cast operator (double[]) .

System.out.println( ((double[])B)[0] + " " +((double[])B)[1]);

Placement of parentheses is critical

Note also that due to precedence issues, the placement of both sets of parentheses is critical in the above code fragment. You must downcast thereference variable before applying the index to that variable.

Back to Question 10

Answer 9

C. 1 2

Explanation 9

General array casting rule

The general rule for casting array references (for arrays whose declared type is the name of a class or an interface) is:

A reference to an array object can be cast to another array type if the elements of the referenced array are of a type that can be cast to the typeof the elements of the specified array type.

Old rules apply here also

Thus, the general rules covering conversion and casting up and down the inheritance hierarchy and among classes that implement the same interfaces alsoapply to the casting of references to array objects.

A reference to an object can be cast down the inheritance hierarchy to the actual class of the object. Therefore, an array reference can also be cast downthe inheritance hierarchy to the declared class for the array object.

This program declares a reference to, creates, and populates an array of the class type Subclass . This reference is assigned to an array reference of a type that is a superclass of the actual class type of the array. Then the superclassreference is downcast to the actual class type of the array and assigned to a different reference variable. This third reference variable is used tosuccessfully access and display the contents of the elements in the array.

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
yes that's correct
I think
Nasa has use it in the 60's, copper as water purification in the moon travel.
nanocopper obvius
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
analytical skills graphene is prepared to kill any type viruses .
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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