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Exercise Write a recursive method to compute the n'th Fibonacci number:

f i b ( 0 ) = 0 , f i b ( 1 ) = 1 , f i b ( n ) = f i b ( n - 1 ) + f i b ( n - 2 ) for n > 1 .

Exercise Write a more efficient nonrecursive method for the same function.

Calling methods on an object

Concept Nonstatic methods defined in a class must be invoked on an object of the class. A reference to the object becomes an implicit actual parameter that initializes a formal variable called this in the method. The variable this need not be explicitly mentioned when accessing fields of the object unless there is an ambiguity.

Program: Method05.java

// Learning Object Method05 //    calling methods on an objectclass Song {     int seconds;      Song(int s) {        seconds = s;     }      double computePrice(double pricePerSecond) {       return seconds * pricePerSecond;     }}  public class Method05 {     public static void main(/*String[] args*/) {         Song song1 = new Song(164);        Song song2 = new Song(103);         double price1 = song1.computePrice(0.01);        double price2 = song2.computePrice(0.02);         System.out.println(price1);        System.out.println(price2);     }}

This program computes the cost of a song as the product of its length in seconds and the price per second. A class Song is defined to encapsulate the field seconds and the method computePrice .

  • Two objects of class Song are instantiated and references to them are assigned to the variables song1 and song2 .
  • The method computePrice is called on the object referenced by song1 . In Jeliot this is visualized by an arrow to the object placed in the Expression Evaluation Area followed by a period and the method name and parameters.
  • An activation record is allocated containing two formal parameters: this is initialized by the implicit reference and pricePerSecond is initialized from the actual parameter.
  • The reference in the parameter this is used to obtain the value of the field seconds . An expression is evaluated and its value returned.
  • The activation record is deallocated and the value returned is stored in the variable price1 .
  • A second call to the method is executed in exactly the same way, except that it is called on the object referenced by song2 .
  • The values of price1 and price2 are printed.

Exercise Modify the method so that the formal parameter is also named seconds . Yes, it can be done! (Hint: read the Concept paragraph above.)

Calling a method on the same object

Concept A nonstatic method defined in a class that is invoked on an object of the class can invoke another such method on the same object. The object for the second call is the same as the one on the first call,namely, the only referenced by this . There is no need to explicitly write this and the object may be accessed implicitly.

Program: Method06A.java

// Learning Object Method06A //    calling a method on the same objectclass Song {     int seconds;      Song(int s) {        seconds = s;     }      boolean discount(int s) {        return s > 300;     }      double computePrice(double pricePerSecond) {        double price = seconds * pricePerSecond;         if (discount(seconds))            price = price * 0.9;         return price;    } }  public class Method06A {    public static void main(/*String[] args*/) {        Song song1 = new Song(164);         Song song2 = new Song(403);        double price1 = song1.computePrice(0.01);         double price2 = song2.computePrice(0.01);        System.out.println(price1);         System.out.println(price2);    } }

Questions & Answers

find the 15th term of the geometric sequince whose first is 18 and last term of 387
Jerwin Reply
The given of f(x=x-2. then what is the value of this f(3) 5f(x+1)
virgelyn Reply
hmm well what is the answer
how do they get the third part x = (32)5/4
kinnecy Reply
can someone help me with some logarithmic and exponential equations.
Jeffrey Reply
sure. what is your question?
okay, so you have 6 raised to the power of 2. what is that part of your answer
I don't understand what the A with approx sign and the boxed x mean
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
I'm not sure why it wrote it the other way
I got X =-6
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
oops. ignore that.
so you not have an equal sign anywhere in the original equation?
is it a question of log
Commplementary angles
Idrissa Reply
im all ears I need to learn
right! what he said ⤴⤴⤴
what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
Kevin Reply
a perfect square v²+2v+_
Dearan Reply
kkk nice
Abdirahman Reply
algebra 2 Inequalities:If equation 2 = 0 it is an open set?
Kim Reply
or infinite solutions?
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Embra Reply
if |A| not equal to 0 and order of A is n prove that adj (adj A = |A|
Nancy Reply
rolling four fair dice and getting an even number an all four dice
ramon Reply
Kristine 2*2*2=8
Bridget Reply
Differences Between Laspeyres and Paasche Indices
Emedobi Reply
No. 7x -4y is simplified from 4x + (3y + 3x) -7y
Mary Reply
how do you translate this in Algebraic Expressions
linda Reply
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris 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
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Learning objects for java (with jeliot). OpenStax CNX. Dec 28, 2009 Download for free at http://cnx.org/content/col10915/1.2
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