<< Chapter < Page Chapter >> Page >

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

Clone

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

physiological Psychology
Nwosu Reply
How can I develope my cognitive domain
Amanyire Reply
why is communication effective
Dakolo Reply
Communication is effective because it allows individuals to share ideas, thoughts, and information with others.
effective communication can lead to improved outcomes in various settings, including personal relationships, business environments, and educational settings. By communicating effectively, individuals can negotiate effectively, solve problems collaboratively, and work towards common goals.
it starts up serve and return practice/assessments.it helps find voice talking therapy also assessments through relaxed conversation.
miss
Every time someone flushes a toilet in the apartment building, the person begins to jumb back automatically after hearing the flush, before the water temperature changes. Identify the types of learning, if it is classical conditioning identify the NS, UCS, CS and CR. If it is operant conditioning, identify the type of consequence positive reinforcement, negative reinforcement or punishment
Wekolamo Reply
please i need answer
Wekolamo
because it helps many people around the world to understand how to interact with other people and understand them well, for example at work (job).
Manix Reply
Agreed 👍 There are many parts of our brains and behaviors, we really need to get to know. Blessings for everyone and happy Sunday!
ARC
A child is a member of community not society elucidate ?
JESSY Reply
Isn't practices worldwide, be it psychology, be it science. isn't much just a false belief of control over something the mind cannot truly comprehend?
Simon Reply
compare and contrast skinner's perspective on personality development on freud
namakula Reply
Skinner skipped the whole unconscious phenomenon and rather emphasized on classical conditioning
war
explain how nature and nurture affect the development and later the productivity of an individual.
Amesalu Reply
nature is an hereditary factor while nurture is an environmental factor which constitute an individual personality. so if an individual's parent has a deviant behavior and was also brought up in an deviant environment, observation of the behavior and the inborn trait we make the individual deviant.
Samuel
I am taking this course because I am hoping that I could somehow learn more about my chosen field of interest and due to the fact that being a PsyD really ignites my passion as an individual the more I hope to learn about developing and literally explore the complexity of my critical thinking skills
Zyryn Reply
good👍
Jonathan
and having a good philosophy of the world is like a sandwich and a peanut butter 👍
Jonathan
generally amnesi how long yrs memory loss
Kelu Reply
interpersonal relationships
Abdulfatai Reply
What would be the best educational aid(s) for gifted kids/savants?
Heidi Reply
treat them normal, if they want help then give them. that will make everyone happy
Saurabh
What are the treatment for autism?
Magret Reply
hello. autism is a umbrella term. autistic kids have different disorder overlapping. for example. a kid may show symptoms of ADHD and also learning disabilities. before treatment please make sure the kid doesn't have physical disabilities like hearing..vision..speech problem. sometimes these
Jharna
continue.. sometimes due to these physical problems..the diagnosis may be misdiagnosed. treatment for autism. well it depends on the severity. since autistic kids have problems in communicating and adopting to the environment.. it's best to expose the child in situations where the child
Jharna
child interact with other kids under doc supervision. play therapy. speech therapy. Engaging in different activities that activate most parts of the brain.. like drawing..painting. matching color board game. string and beads game. the more you interact with the child the more effective
Jharna
results you'll get.. please consult a therapist to know what suits best on your child. and last as a parent. I know sometimes it's overwhelming to guide a special kid. but trust the process and be strong and patient as a parent.
Jharna
what is learning? discuss how any three scholars propounded on how learning is
Grace Reply
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, Learning objects for java (with jeliot). OpenStax CNX. Dec 28, 2009 Download for free at http://cnx.org/content/col10915/1.2
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Learning objects for java (with jeliot)' conversation and receive update notifications?

Ask