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A new object of the target class

However, the code in Listing 27 goes beyond that. In particular, the code in Listing 27 creates a new object from which to get the data that is to be plotted.

In some cases, this may be required, depending on the nature of the class from which that object is instantiated. In other cases, it may not be necessary,and could slow down the re-plotting process.

If your class doesn't contain counters or other variables that need to be re-initialized whenever you re-plot, you could probably safely remove or disablethe code in Listing 27 . This will make the program run faster, although you may not be able to see the difference.

The remainder of the event handler

The remaining code in the event handler is shown in Listing 28 .

Listing 28. The remainder of the event handler.
//Set plotting parameters using // data from the text fields.xMin = Double.parseDouble( xMinTxt.getText());xMax = Double.parseDouble( xMaxTxt.getText());yMin = Double.parseDouble( yMinTxt.getText());yMax = Double.parseDouble( yMaxTxt.getText());xTicInt = Double.parseDouble( xTicIntTxt.getText());yTicInt = Double.parseDouble( yTicIntTxt.getText());xCalcInc = Double.parseDouble( xCalcIncTxt.getText());//Calculate new values for the // length of the tic marks on the// axes. If too small on x-axis, // a default value is used later.xTicLen = (yMax-yMin)/50; yTicLen = (xMax-xMin)/50;//Repaint the plotting areas for(int cnt = 0;cnt<number; cnt++){ canvases[cnt].repaint(); }//end for loop}//end actionPerformed

This code is very straightforward. It performs the following actions:

  • Get new plotting parameters from the text fields.
  • Perform some calculations.
  • Cause each of the MyCanvas objects to be repainted using the new plotting parameters.

Again, I will let the comments provide any necessary explanations.

That brings us to the most interesting part of the program, the extended Canvas class.

Beginning of the class named MyCanvas

The class named MyCanvas is an inner class of the GUI class, which is used to override the paint method in each of the plotting areas shown in Figure 1 .

(Virtually all graphics operations in Java, other than those involving standard GUI components, are implemented by overriding the paint method on an object.)

The beginning of this class definition is shown in Listing 29 .

Listing 29. Beginning of the class named MyCanvas.
class MyCanvas extends Canvas{ int cnt;//object number//Factors to convert from double // values to integer pixel locations.double xScale; double yScale;MyCanvas(int cnt){//save obj number this.cnt = cnt;}//end constructor

Floating data vs. pixels

Most of the calculations in this program are performed on data of type double . However, graphics operations are ultimately performed in terms integer numbers of pixels. The code in Listing 29 declares scale factors used later to convert from double values to integer pixel locations.

Questions & Answers

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.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
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.
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
for teaching engĺish at school how nano technology help us
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
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?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
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
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how did you get the value of 2000N.What calculations are needed to arrive at it
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