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Exercise Move the declaration of equals to class BParticle , changing the code as needed. What now is the value of c1.equals(b1) ? Explain.


Concept Assigning a variable containing a reference to another of the same type merely copies thereference so that two fields refer to the same object. The method clone is used to copy the content of an object into a new one. clone is defined in class Object and can be overridden in any class definition.

Program: Inheritance08.java

// Learning Object Inheritance08 //    cloneclass Particle implements Cloneable {     int position;      Particle(int p) {        position = p;     }      void newPosition(int delta) {        position = position + delta;     }      protected Object clone() {        try {             Particle p = (Particle) super.clone();            p.newPosition(10);             return p;        }         catch (CloneNotSupportedException e) {            e.printStackTrace();             throw new Error();        }     }}  class Inheritance08 {     public static void main(String[] args) {         Particle p1 = new Particle(20);        Particle p2 = p1;         p1.newPosition(10);        System.out.println(p1.position);         System.out.println(p2.position);          Particle p3 = (Particle) p1.clone();        System.out.println(p1.position);         System.out.println(p3.position);          p3.newPosition(10);        System.out.println(p1.position);         System.out.println(p3.position);    } }

clone is overridden in class Particle . The class must implement the interface Cloneable , the method of the superclass should be called, and we have to take intoaccount that the method might raise an exception. The method returns the object returned by superclass method after calling newPosition .

  • An object of class Particle is allocated and its reference assigned to the field p1 .
  • An assignment statement copies this reference to the field p2 . Check that they have the same value.
  • The method newPosition is called on p1 , but the value of p2.position is also changed, showing that the two fields point to the same object.
  • An object of class Particle is obtained by calling p1.clone() and its reference assigned to the field p3 . Since clone returns a value of type Object , it must be cast to type Particle before the assignment. Check that the objects referenced by p1 and p3 have different values.
  • Calling p3.newPosition changes only the field in the object referenced by p3 and not the separate object referenced by p1 .

Exercise The method clone can perform arbitrary computation. Modify the program so that new objects are initialized withthe absolute value of the field of the object that is being cloned.

Overloading vs. overriding

Concept Overloading is the use of the same method name with a different parameter signature. Overriding is the use in a subclass of the same method name with the same parameter signature as a method of the superclass.

Program: Inheritance09.java

// Learning Object Inheritance09 //    overloading vs. overridingclass Particle {     int position;      Particle(int p) {        position = p;     }      void newPosition(int delta) {        position = position + delta;     }}  class AParticle extends Particle {     double spin;      AParticle(int p, double s) {        super(p);         spin = s;    }      void newPosition(int delta) {     if (spin < delta)             position = position + delta;    }      void newPosition(double delta) {     if (position < delta)             spin = spin + delta;    } }  class Inheritance09 {    public static void main(/*String[] args*/) {        Particle  p = new Particle(10);         AParticle a1 = new AParticle(20, -1.0);        AParticle a2 = new AParticle(20, -1.0);          p.newPosition(10);         int pPosition = p.position;        a1.newPosition(10);         int a1Position = a1.position;        a2.newPosition(10.0);         int a2Position = a2.position;    } }

The method newPosition(int delta) is declared in Particle and overridden in AParticle . It is also overloaded by a method with the same name takes a parameter of type double .

  • After allocating three objects p , a1 and a2 , newPosition is called on each one.
  • p.newPosition calls the method declared in class Particle .
  • a1.newPosition calls the method declared in class AParticle that overrides the method in Particle .
  • a2.newPosition calls the overloaded method because the actual parameter is of type double .

Exercise At the end of the program add an assignment p = a1 . Add the method invocations p.newPosition(10) and p.newPosition(10.0) in the main method. Explain what happens.

Questions & Answers

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?
Commplementary angles
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what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
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a perfect square v²+2v+_
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algebra 2 Inequalities:If equation 2 = 0 it is an open set?
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or infinite solutions?
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
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Kristine 2*2*2=8
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Differences Between Laspeyres and Paasche Indices
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No. 7x -4y is simplified from 4x + (3y + 3x) -7y
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J, combine like terms 7x-4y
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how do you translate this in Algebraic Expressions
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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
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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?
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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?
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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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