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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

who was the first nanotechnologist
Lizzy Reply
k
Veysel
technologist's thinker father is Richard Feynman but the literature first user scientist Nario Tagunichi.
Veysel
Norio Taniguchi
puvananathan
Interesting
Andr
I need help
Richard
anyone have book of Abdel Salam Hamdy Makhlouf book in pdf Fundamentals of Nanoparticles: Classifications, Synthesis
Naeem Reply
what happen with The nano material on The deep space.?
pedro Reply
It could change the whole space science.
puvananathan
the characteristics of nano materials can be studied by solving which equation?
sibaram Reply
plz answer fast
sibaram
synthesis of nano materials by chemical reaction taking place in aqueous solvents under high temperature and pressure is call?
sibaram
hydrothermal synthesis
ISHFAQ
how can chip be made from sand
Eke Reply
is this allso about nanoscale material
Almas
are nano particles real
Missy Reply
yeah
Joseph
Hello, if I study Physics teacher in bachelor, can I study Nanotechnology in master?
Lale Reply
no can't
Lohitha
where is the latest information on a no technology how can I find it
William
currently
William
where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
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..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
has a lot of application modern world
Kamaluddeen
yes
narayan
what is variations in raman spectra for nanomaterials
Jyoti Reply
ya I also want to know the raman spectra
Bhagvanji
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.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
STM - Scanning Tunneling Microscope.
puvananathan
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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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