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Listing 4 . The class named MyClass.
class MyClass{ int data;MyClass(){ data = 0;}//end noarg constructor MyClass(int data){this.data = data; }//end parameterized constructorpublic String toString(){ return "" + data;}//end overridden toString() }//end MyClass

The class named TheComparator

That brings us to the class named TheComparator from which the Comparator object was instantiated and passed to the constructor for the TreeSet object in Listing 2 . The declaration for the class named TheComparator is shown in Listing 5 .

Listing 5 . Beginning of the class named TheComparator.
class TheComparator implements Comparator,Serializable{

As you can see, the class named TheComparator implements both the Comparator interface and the Serializable interface.

Implementing the Comparator interface

By implementing the Comparator interface, an object instantiated from the class is eligible to be passed to the constructor for a TreeSet object, which requires an incoming parameter of type Comparator .

Implementing the Serializable interface

Here is what Oracle has to say about implementing the Serializable interface:

"Note: It is generally a good idea for comparators to implement java.io.Serializable, as they may be used as ordering methods inserializable data structures (like TreeSet, TreeMap). In order for the data structure to serialize successfully, the comparator (if provided) mustimplement Serializable."

Since the Serializable interface doesn't declare any methods, implementing the interface simply requires a declaration that the interface isbeing implemented.

Methods of the Comparator interface

The Comparator interface declares the two methods listed below:

  • public int compare (Object o1, Object o2)
  • public boolean equals (Object obj)

As is always the case when implementing interfaces, a class that implements the Comparator interface must provide concrete definitions for both of these methods.

The compare method

The beginning of the compare method is shown in Listing 6 .

Listing 6 . Beginning of the compare method.
public int compare(Object o1,Object o2){ if(!(o1 instanceof MyClass))throw new ClassCastException(); if(!(o2 instanceof MyClass))throw new ClassCastException();

The purpose of a Comparator is to compare the values stored in the instance variables of two objects and to return a value indicating which objectis greater .

Specialization is required

Generally speaking, therefore, a Comparator object must be specialized to deal with a particular type of object. That type could be

  • A specific class from which the object is instantiated,
  • A specific interface implemented by the class from which the object is instantiated, or perhaps
  • A specific superclass of the class from which the object is instantiated.

The code in Listing 6 confirms that both of the objects to be compared are of the correct type, which in this case is type MyClass .

Must gain access to instance variables

Regardless of how the type is established, the code in the compare method of the Comparator object must gain access to the instance variables of the two objects passed to the compare method as type Object . This normally requires that a downcast be performed on the incoming object references.

Questions & Answers

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
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
characteristics of micro business
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 ?
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.
what is the actual application of fullerenes nowadays?
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.
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.
is Bucky paper clear?
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.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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