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The size issue

Here is some of what the Oracle documentation for the LinkedList class has to say about the size issue for this version of the toArray method.

"If the list fits in the specified array, it is returned therein. Otherwise, a new array is allocated with the runtime type of the specifiedarray and the size of this list. If the list fits in the specified array with room to spare (i.e., the array has more elements than the list), theelement in the array immediately following the end of the collection is set to null. This is useful in determining the length of the list only if thecaller knows that the list does not contain any null elements."

So, what did I do?

Knowing all of this in advance, I purposely caused the size of the JComponent array to be larger (by two elements) than the number of elements in the collection. Therefore, the array that I passed to the toArray method was populated and a reference to that populated array was returned.

(Had my array been smaller than the number of elements in the collection, the toArray method would have created and populated a new array of typeJComponent and would have returned a reference to that new array object. In that case, my array would have been used by the toArray method only for the purposeof determining the runtime type of my array.)

More information from Oracle

Here is some additional information about the toArray method provided by the Oracle documentation for the Collection interface:

"If this collection makes any guarantees as to what order its elements are returned by its iterator, this method must return the elements in thesame order."

Because the iterator for a LinkedList object returns the elements in increasing index order, the toArray method, in this case, copies the element at each index position in the collection into the element at the sameindex position in the array. Thus, reference values are copied from each element in the collection into the first six elements in the array.

The output

The output produced by the code in Listing 5 is shown below:

New array contents B0 B1 L2 B3 B4 L5 null 17

You will note that the first six elements in the array match the six elements in the collection (the initial values placed in the array earlier when the array was instantiated have been overwritten).

You will also note that the value of the seventh element in the array (index value 6) has been overwritten with a null reference.

Demonstrates same array was used

Note finally that the last element in the array was not overwritten. It still contains the value placed there when the array object was instantiated. Thisdemonstrates that the array that I passed to the toArray method was populated with the collection data, and a reference to that array was returnedby the toArray method.

What if the array was too small?

Had my array been too small, it would have been discarded by the toArray method. The toArray method would have created and populated a new array object of the correct size and runtime type, and would have returned a referenceto that new array.

Questions & Answers

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
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
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
Rafiq
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
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
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
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
How can I make nanorobot?
Lily
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
how can I make nanorobot?
Lily
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
in a comparison of the stages of meiosis to the stage of mitosis, which stages are unique to meiosis and which stages have the same event in botg meiosis and mitosis
Leah Reply
Researchers demonstrated that the hippocampus functions in memory processing by creating lesions in the hippocampi of rats, which resulted in ________.
Mapo Reply
The formulation of new memories is sometimes called ________, and the process of bringing up old memories is called ________.
Mapo 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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