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Making the objects distinguishable

After the code in Listing 3 has been executed, the buttons and labels are indistinguishable on the basis of the null value of their toolTipText property.

The code in Listing 4 deals with this issue. This code uses the setToolTipText method to store a unique String value in the toolTipText property of the object referred to by each of the elements in the collection.

Listing 4 . Making the objects distinguishable.
Iterator iter = ref.iterator(); int cnt = 0;JComponent refVar; while(iter.hasNext()){refVar = (JComponent)iter.next(); if(refVar instanceof JButton){refVar.setToolTipText("B"+cnt++); }else{refVar.setToolTipText("L" + cnt++); }//end else}//end while loop }//end fillIt()

Identifying the buttons and labels

In addition to storing a unique value in the toolTipText property of the object referred to by each element, the code in Listing 4 also makes it possible to distinguish between the JButton objects and the JLabel objects. This is accomplished by including an upper-case "B" in the propertyvalue for each JButton , and including an upper-case "L" in the property value for each JLabel button.

Why populate this way?

This approach to population is, admittedly, a little bit of an overkill for illustrating what I want to illustrate in this program. However, I plan to usethe same fillIt method in the sample program in the next module, and it won't be an overkill there.

Display the collection

The code in Listing 2 above calls the showCollection method to display the contents of the populated LinkedList collection. The showCollection method is shown in Listing 5

Listing 5 . The showCollection method.
void showCollection(Collection ref){ Iterator iter = ref.iterator();while(iter.hasNext()){ System.out.print(((JComponent)iter.next()).getToolTipText() + " "); }//end while loopSystem.out.println(); }//end showCollection

By now, you should have no difficulty understanding the code in Listing 5 . This code gets an iterator on the incoming reference of type Collection . The code then uses that iterator to gain access to each element in succession,displaying the String value of the toolTipText property belonging to a particular object during each iteration.

Downcast is required

Note that the next method of the Iterator interface returns a reference to the next element in the collection, as type Object . (Remember, Generics were not used to populate this collection.)

In order to call the getToolTipText method on the returned reference, the reference must be downcast to type JComponent . Since both JButton and JLabel extend JComponent , and the getToolTipText method is declared in the JComponent class, it is not necessary to be concerned as to whether an object is type JButton or type JLabel to display the value of the toolTipText property. (This is an example of polymorphic behavior based on class inheritance.)

The output for the collection

The output produced by the code in Listing 2 is shown below:

Collection contentsB0 B1 L2 B3 B4 L5

By examining the "B" and "L" characters in this output, you can identify the JButton objects and the JLabel objects.

Questions & Answers

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.
Damian
yes that's correct
Professor
I think
Professor
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
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
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
hi
Loga
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
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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