Polymorphism vs Overriding vs Overloading

Question

In terms of Java  when someone asks       what is polymorphism    Would overloading or overriding be an acceptable answer   I think there is a bit more to it than that    IF you had a abstract base class that defined a method with no implementation  and you defined that method in the sub class  is that still overridding   I think overloading is not the right answer for sure

User · Answer

Polymorphism relates to the ability of a language to have different object treated uniformly by using a single interfaces; as such it is related to overriding, so the interface (or the base class) is polymorphic, the implementor is the object which overrides (two faces of the same medal)

anyway, the difference between the two terms is better explained using other languages, such as c++: a polymorphic object in c++ behaves as the java counterpart if the base function is virtual, but if the method is not virtual the code jump is resolved statically, and the true type not checked at runtime so, polymorphism include the ability for an object to behave differently depending on the interface used to access it; let me make an example in pseudocode:

class animal {
    public void makeRumor(){
        print("thump");
    }
}
class dog extends animal {
    public void makeRumor(){
        print("woff");
    }
}

animal a = new dog();
dog b = new dog();

a.makeRumor() -> prints thump
b.makeRumor() -> prints woff

(supposing that makeRumor is NOT virtual)

java doesn't truly offer this level of polymorphism (called also object slicing).

animal a = new dog(); dog b = new dog();

a.makeRumor() -> prints thump
b.makeRumor() -> prints woff

on both case it will only print woff.. since a and b is refering to class dog

User · Answer

import java io IOException   class Super        protected Super getClassName Super s  throws IOException           System out println this getClass   getSimpleName       - I m parent            return null            class SubOne extends Super         Override     protected Super getClassName Super s             System out println this getClass   getSimpleName       - I m Perfect Overriding            return null            class SubTwo extends Super         Override     protected Super getClassName Super s  throws NullPointerException           System out println this getClass   getSimpleName       - I m Overriding and Throwing Runtime Exception            return null            class SubThree extends Super         Override     protected SubThree getClassName Super s            System out println this getClass   getSimpleName      - I m Overriding and Returning SubClass Type            return null            class SubFour extends Super         Override     protected Super getClassName Super s  throws IOException           System out println this getClass   getSimpleName      - I m Overriding and Throwing Narrower Exception             return null            class SubFive extends Super         Override     public Super getClassName Super s            System out println this getClass   getSimpleName      - I m Overriding and have broader Access             return null            class SubSix extends Super        public Super getClassName Super s  String ol            System out println this getClass   getSimpleName      - I m Perfect Overloading             return null            class SubSeven extends Super        public Super getClassName SubSeven s            System out println this getClass   getSimpleName      - I m Perfect Overloading because Method signature  Argument  changed             return null            public class Test       public static void main String   args  throws Exception            System out println  Overriding n             Super s1   new SubOne    s1 getClassName null            Super s2   new SubTwo    s2 getClassName null            Super s3   new SubThree    s3 getClassName null            Super s4   new SubFour    s4 getClassName null            Super s5   new SubFive    s5 getClassName null            System out println  Overloading n             SubSix s6   new SubSix    s6 getClassName null  null            s6   new SubSix    s6 getClassName null            SubSeven s7   new SubSeven    s7 getClassName s7            s7   new SubSeven    s7 getClassName new Super

User · Answer

The clearest way to express polymorphism is via an abstract base class  or interface   public abstract class Human            public abstract void goPee        This class is abstract because the goPee   method is not definable for Humans   It is only definable for the subclasses Male and Female   Also  Human is an abstract concept  mdash  You cannot create a human that is neither Male nor Female   It   s got to be one or the other   So we defer the implementation by using the abstract class   public class Male extends Human           Override     public void goPee            System out println  Stand Up              and  public class Female extends Human           Override     public void goPee            System out println  Sit Down              Now we can tell an entire room full of Humans to go pee   public static void main String   args       ArrayList lt Human gt  group   new ArrayList lt Human gt         group add new Male         group add new Female                add more            tell the class to take a pee break     for  Human person   group  person goPee        Running this would yield   Stand Up Sit Down

User · Answer

Specifically saying overloading or overriding doesn t give the full picture   Polymorphism is simply the ability of an object to specialize its behavior based on its type     I would disagree with some of the answers here in that overloading is a form of polymorphism  parametric polymorphism  in the case that a method with the same name can behave differently give different parameter types   A good example is operator overloading   You can define     to accept different types of parameters -- say strings or int s -- and based on those types      will behave differently   Polymorphism also includes inheritance and overriding methods  though they can be abstract or virtual in the base type   In terms of inheritance-based polymorphism  Java only supports single class inheritance limiting it polymorphic behavior to that of a single chain of base types   Java does support implementation of multiple interfaces which is yet another form of polymorphic behavior

User · Answer

overriding is more like hiding an inherited method by declaring a method with the same name and signature as the upper level method  super method   this  adds a polymorphic behaviour to the  class   in other words the decision to choose wich level method to be called  will be made at run time not on compile time   this leads to  the concept of interface and implementation

User · Answer

Polymorphism means more than one form  same object performing different operations according to the requirement   Polymorphism can be achieved by using two ways  those are   Method overriding Method overloading   Method overloading means writing two or more methods in the same class by using same method name  but the passing parameters is different   Method overriding means we use the method names in the different classes that means parent class method is used in the child class   In Java to achieve polymorphism a super class reference variable can hold the sub class object   To achieve the polymorphism every developer must use the same method names in the project

User · Answer

Although  Polymorphism is already explained in great details in this post but I would like put more emphasis on why part of it       Why Polymorphism is so important in any OOP language    Let   s try to build a simple application for a TV with and without Inheritance Polymorphism  Post each version of the application  we do a small retrospective   Supposing  you are a software engineer at a TV company and you are asked to write software for Volume  Brightness and Colour controllers to increase and decrease their values on user command   You start with writing classes for each of these features by adding   set - To set a value of a controller  Supposing this has controller specific code  get - To get a value of a controller  Supposing this has controller specific code  adjust - To validate the input and setting a controller  Generic validations   independent of controllers  user input mapping with controllers  - To get user input and invoking controllers accordingly       Application Version 1   import java util Scanner      class VolumeControllerV1       private int value      int get                return value            void set int value            System out println  Old value of VolumeController  t  this value           this value   value          System out println  New value of VolumeController  t  this value             void adjust int value             int temp   this get            if   value  gt  0   amp  amp   temp  gt   100        value  lt  0   amp  amp   temp  lt   0                     System out println  Can not adjust any further                return                    this set temp   value           class  BrightnessControllerV1       private int value      int get                return value            void set int value            System out println  Old value of BrightnessController  t  this value           this value   value          System out println  New value of BrightnessController  t  this value             void adjust int value             int temp   this get            if   value  gt  0   amp  amp   temp  gt   100        value  lt  0   amp  amp   temp  lt   0                     System out println  Can not adjust any further                return                    this set temp   value           class ColourControllerV1          private int value      int get                return value            void set int value            System out println  Old value of ColourController  t  this value           this value   value          System out println  New value of ColourController  t  this value             void adjust int value             int temp   this get            if   value  gt  0   amp  amp   temp  gt   100        value  lt  0   amp  amp   temp  lt   0                     System out println  Can not adjust any further                return                    this set temp   value                        There can be n number of controllers       public class TvApplicationV1       public static void main String   args             VolumeControllerV1 volumeControllerV1   new VolumeControllerV1            BrightnessControllerV1 brightnessControllerV1   new BrightnessControllerV1            ColourControllerV1 colourControllerV1   new ColourControllerV1              OUTER  while true                Scanner sc new Scanner System in               System out println   Enter your option  n Press 1 to increase volume  n Press 2 to decrease volume                System out println   Press 3 to increase brightness  n Press 4 to decrease brightness                System out println   Press 5 to increase color  n Press 6 to decrease color                System out println  Press any other Button to shutdown                int button   sc nextInt                switch  button                    case  1                           volumeControllerV1 adjust 5                       break                                    case 2                        volumeControllerV1 adjust -5                       break                                    case  3                           brightnessControllerV1 adjust 5                       break                                    case 4                        brightnessControllerV1 adjust -5                       break                                    case  5                           colourControllerV1 adjust 5                       break                                    case 6                    colourControllerV1 adjust -5                   break                            default                  System out println  Shutting down                               break OUTER                             Now you have our first version of working application ready to be deployed  Time to analyze the work done so far      Issues in TV Application Version 1    Adjust int value  code is duplicate in all three classes  You would like to minimize the code duplicity   But you did not think of common code and moving it to some super class to avoid duplicate code    You decide to live with that as long as your application works as expected      After sometimes  your Boss comes back to you and asks you to add reset functionality to the existing application  Reset would set all 3 three controller to their respective default values    You start writing a new class  ResetFunctionV2  for the new functionality and map the user input mapping code for this new feature      Application Version 2   import java util Scanner  class VolumeControllerV2           private int defaultValue   25      private int value       int getDefaultValue             return defaultValue            int get                return value            void set int value            System out println  Old value of VolumeController  t  this value           this value   value          System out println  New value of VolumeController  t  this value             void adjust int value             int temp   this get            if   value  gt  0   amp  amp   temp  gt   100        value  lt  0   amp  amp   temp  lt   0                     System out println  Can not adjust any further                return                    this set temp   value           class  BrightnessControllerV2          private int defaultValue   50      private int value      int get                return value            int getDefaultValue             return defaultValue            void set int value            System out println  Old value of BrightnessController  t  this value           this value   value          System out println  New value of BrightnessController  t  this value             void adjust int value             int temp   this get            if   value  gt  0   amp  amp   temp  gt   100        value  lt  0   amp  amp   temp  lt   0                     System out println  Can not adjust any further                return                    this set temp   value           class ColourControllerV2           private int defaultValue   40      private int value      int get                return value            int getDefaultValue             return defaultValue            void set int value            System out println  Old value of ColourController  t  this value           this value   value          System out println  New value of ColourController  t  this value             void adjust int value             int temp   this get            if   value  gt  0   amp  amp   temp  gt   100        value  lt  0   amp  amp   temp  lt   0                     System out println  Can not adjust any further                return                    this set temp   value            class ResetFunctionV2        private VolumeControllerV2 volumeControllerV2       private BrightnessControllerV2 brightnessControllerV2      private ColourControllerV2 colourControllerV2       ResetFunctionV2 VolumeControllerV2 volumeControllerV2  BrightnessControllerV2 brightnessControllerV2  ColourControllerV2 colourControllerV2             this volumeControllerV2   volumeControllerV2          this brightnessControllerV2   brightnessControllerV2          this colourControllerV2   colourControllerV2            void onReset                volumeControllerV2 set volumeControllerV2 getDefaultValue             brightnessControllerV2 set brightnessControllerV2 getDefaultValue             colourControllerV2 set colourControllerV2 getDefaultValue                         so on          There can be n number of controllers          public class TvApplicationV2       public static void main String   args             VolumeControllerV2 volumeControllerV2   new VolumeControllerV2            BrightnessControllerV2 brightnessControllerV2   new BrightnessControllerV2            ColourControllerV2 colourControllerV2   new ColourControllerV2             ResetFunctionV2 resetFunctionV2   new ResetFunctionV2 volumeControllerV2  brightnessControllerV2  colourControllerV2            OUTER  while true                Scanner sc new Scanner System in               System out println   Enter your option  n Press 1 to increase volume  n Press 2 to decrease volume                System out println   Press 3 to increase brightness  n Press 4 to decrease brightness                System out println   Press 5 to increase color  n Press 6 to decrease color                System out println   Press 7 to reset TV  n Press any other Button to shutdown                int button   sc nextInt                switch  button                    case  1                           volumeControllerV2 adjust 5                       break                                    case 2                        volumeControllerV2 adjust -5                       break                                    case  3                           brightnessControllerV2 adjust 5                       break                                    case 4                        brightnessControllerV2 adjust -5                       break                                    case  5                           colourControllerV2 adjust 5                       break                                    case 6                        colourControllerV2 adjust -5                       break                                    case 7                        resetFunctionV2 onReset                        break                                    default                      System out println  Shutting down                                   break OUTER                                     So you have your application ready with Reset feature  But  now you start realizing that      Issues in TV Application Version 2    If a new controller is introduced to the product  you have to change Reset feature code  If the count of the controller grows very high  you would have issue in holding the references of the controllers  Reset feature code is tightly coupled with all the controllers Class   s code to get and set default values   Reset feature class  ResetFunctionV2  can access other method of the Controller class   s  adjust  which is undesirable       At the same time  You hear from you Boss that you might have to add a feature wherein each of controllers  on start-up  needs to check for the latest version of driver from company   s hosted driver repository via internet    Now you start thinking that this new feature to be added resembles with Reset feature and Issues of Application  V2  will be multiplied if you don   t re-factor your application   You start thinking of using inheritance so that you can take advantage from polymorphic ability of JAVA and you add a new abstract class  ControllerV3  to   Declare the signature of get and set method  Contain adjust method implementation which was earlier replicated among all the controllers  Declare setDefault method so that reset feature can be easily implemented leveraging Polymorphism    With these improvements  you have version 3 of your TV application ready with you      Application Version 3   import java util ArrayList  import java util List  import java util Scanner   abstract class ControllerV3       abstract void set int value       abstract int get        void adjust int value             int temp   this get            if   value  gt  0   amp  amp   temp  gt   100        value  lt  0   amp  amp   temp  lt   0                     System out println  Can not adjust any further                return                    this set temp   value             abstract void setDefault      class VolumeControllerV3 extends ControllerV3          private int defaultValue   25      private int value       public void setDefault             set defaultValue             int get                return value            void set int value            System out println  Old value of VolumeController  t  this value           this value   value          System out println  New value of VolumeController  t  this value           class  BrightnessControllerV3  extends ControllerV3          private int defaultValue   50      private int value       public void setDefault             set defaultValue             int get                return value            void set int value            System out println  Old value of BrightnessController  t  this value           this value   value          System out println  New value of BrightnessController  t  this value           class ColourControllerV3 extends ControllerV3          private int defaultValue   40      private int value       public void setDefault             set defaultValue             int get                return value            void set int value            System out println  Old value of ColourController  t  this value           this value   value          System out println  New value of ColourController  t  this value            class ResetFunctionV3        private List lt ControllerV3 gt  controllers   null       ResetFunctionV3 List lt ControllerV3 gt  controllers             this controllers   controllers            void onReset                for  ControllerV3 controllerV3  this controllers                 controllerV3 setDefault                                  so on          There can be n number of controllers          public class TvApplicationV3       public static void main String   args             VolumeControllerV3 volumeControllerV3   new VolumeControllerV3            BrightnessControllerV3 brightnessControllerV3   new BrightnessControllerV3            ColourControllerV3 colourControllerV3   new ColourControllerV3             List lt ControllerV3 gt  controllerV3s   new ArrayList lt  gt             controllerV3s add volumeControllerV3           controllerV3s add brightnessControllerV3           controllerV3s add colourControllerV3            ResetFunctionV3 resetFunctionV3   new ResetFunctionV3 controllerV3s            OUTER  while true                Scanner sc new Scanner System in               System out println   Enter your option  n Press 1 to increase volume  n Press 2 to decrease volume                System out println   Press 3 to increase brightness  n Press 4 to decrease brightness                System out println   Press 5 to increase color  n Press 6 to decrease color                System out println   Press 7 to reset TV  n Press any other Button to shutdown                int button   sc nextInt                switch  button                    case  1                           volumeControllerV3 adjust 5                       break                                    case 2                        volumeControllerV3 adjust -5                       break                                    case  3                           brightnessControllerV3 adjust 5                       break                                    case 4                        brightnessControllerV3 adjust -5                       break                                    case  5                           colourControllerV3 adjust 5                       break                                    case 6                        colourControllerV3 adjust -5                       break                                    case 7                        resetFunctionV3 onReset                        break                                    default                      System out println  Shutting down                                   break OUTER                                     Although most of the Issue listed in issue list of V2 were addressed except     Issues in TV Application Version 3    Reset feature class  ResetFunctionV3  can access other method of the Controller class   s  adjust  which is undesirable    Again  you think of solving this problem  as now you have another feature  driver update at startup  to implement as well  If you don   t fix it  it will get replicated to new features as well   So you divide the contract defined in abstract class and write 2 interfaces for   Reset feature  Driver Update    And have your 1st concrete class implement them as below     Application Version 4   import java util ArrayList  import java util List  import java util Scanner   interface OnReset       void setDefault      interface OnStart       void checkForDriverUpdate      abstract class ControllerV4 implements OnReset OnStart       abstract void set int value       abstract int get        void adjust int value             int temp   this get            if   value  gt  0   amp  amp   temp  gt   100        value  lt  0   amp  amp   temp  lt   0                     System out println  Can not adjust any further                return                    this set temp   value            class VolumeControllerV4 extends ControllerV4        private int defaultValue   25      private int value       Override     int get                return value            void set int value            System out println  Old value of VolumeController  t  this value           this value   value          System out println  New value of VolumeController  t  this value              Override     public void setDefault             set defaultValue               Override     public void checkForDriverUpdate                System out println  Checking driver update for VolumeController      Done            class  BrightnessControllerV4 extends ControllerV4        private int defaultValue   50      private int value       Override     int get                return value             Override     void set int value            System out println  Old value of BrightnessController  t  this value           this value   value          System out println  New value of BrightnessController  t  this value               Override     public void setDefault             set defaultValue               Override     public void checkForDriverUpdate                System out println  Checking driver update for BrightnessController      Done            class ColourControllerV4 extends ControllerV4        private int defaultValue   40      private int value       Override     int get                return value            void set int value            System out println  Old value of ColourController  t  this value           this value   value          System out println  New value of ColourController  t  this value              Override     public void setDefault             set defaultValue               Override     public void checkForDriverUpdate                System out println  Checking driver update for ColourController      Done            class ResetFunctionV4        private List lt OnReset gt  controllers   null       ResetFunctionV4 List lt OnReset gt  controllers             this controllers   controllers            void onReset                for  OnReset onreset  this controllers                 onreset setDefault                      class InitializeDeviceV4        private List lt OnStart gt  controllers   null       InitializeDeviceV4 List lt OnStart gt  controllers             this controllers   controllers            void initialize                for  OnStart onStart  this controllers                 onStart checkForDriverUpdate                                 so on         There can be n number of controllers        public class TvApplicationV4       public static void main String   args             VolumeControllerV4 volumeControllerV4   new VolumeControllerV4            BrightnessControllerV4 brightnessControllerV4   new BrightnessControllerV4            ColourControllerV4 colourControllerV4   new ColourControllerV4            List lt ControllerV4 gt  controllerV4s   new ArrayList lt  gt             controllerV4s add brightnessControllerV4           controllerV4s add volumeControllerV4           controllerV4s add colourControllerV4            List lt OnStart gt  controllersToInitialize   new ArrayList lt  gt             controllersToInitialize addAll controllerV4s           InitializeDeviceV4 initializeDeviceV4   new InitializeDeviceV4 controllersToInitialize           initializeDeviceV4 initialize             List lt OnReset gt  controllersToReset   new ArrayList lt  gt             controllersToReset addAll controllerV4s           ResetFunctionV4 resetFunctionV4   new ResetFunctionV4 controllersToReset            OUTER  while true                Scanner sc new Scanner System in               System out println   Enter your option  n Press 1 to increase volume  n Press 2 to decrease volume                System out println   Press 3 to increase brightness  n Press 4 to decrease brightness                System out println   Press 5 to increase color  n Press 6 to decrease color                System out println   Press 7 to reset TV  n Press any other Button to shutdown                int button   sc nextInt                switch  button                    case  1                           volumeControllerV4 adjust 5                       break                                    case 2                        volumeControllerV4 adjust -5                       break                                    case  3                           brightnessControllerV4 adjust 5                       break                                    case 4                        brightnessControllerV4 adjust -5                       break                                    case  5                           colourControllerV4 adjust 5                       break                                    case 6                        colourControllerV4 adjust -5                       break                                    case 7                        resetFunctionV4 onReset                        break                                    default                      System out println  Shutting down                                   break OUTER                                        Now all of the issue faced by you got addressed and you realized that with the use of Inheritance and Polymorphism you could    Keep various part of application loosely coupled   Reset or Driver Update feature components  don   t need to be made aware of actual controller classes Volume  Brightness and Colour   any class implementing OnReset or OnStart will be acceptable to Reset or Driver Update feature components respectively   Application enhancement becomes easier  New addition of controller wont impact reset or driver update feature component  and it is now really easy for you to add new ones  Keep layer of abstraction  Now Reset feature can see only setDefault method of controllers and Reset feature can see only checkForDriverUpdate method of controllers    Hope  this helps  -

User · Answer

Polymorphism is a multiple implementations of an object or you could say multiple forms of an object  lets say you have class Animals as the abstract base class and it has a method called movement   which defines the way that the animal moves  Now in reality we have different kinds of animals and they move differently as well some of them with 2 legs  others with 4 and some with no legs  etc   To define different movement   of each animal on earth  we need to apply polymorphism  However  you need to define more classes i e  class Dogs Cats Fish etc  Then you need to extend those classes from the base class Animals and override its method movement   with a new movement functionality based on each animal you have  You can also use Interfaces to achieve that  The keyword in here is overriding  overloading is different and is not considered as polymorphism  with overloading you can define multiple methods  with same name  but with different parameters on same object or class

User · Answer

Polymorphism is the ability of a class instance to behave as if it were an instance of another class in its inheritance tree  most often one of its ancestor classes  For example  in Java all classes inherit from Object  Therefore  you can create a variable of type Object and assign to it an instance of any class   An override is a type of function which occurs in a class which inherits from another class  An override function  replaces  a function inherited from the base class  but does so in such a way that it is called even when an instance of its class is pretending to be a different type through polymorphism  Referring to the previous example  you could define your own class and override the toString   function  Because this function is inherited from Object  it will still be available if you copy an instance of this class into an Object-type variable  Normally  if you call toString   on your class while it is pretending to be an Object  the version of toString which will actually fire is the one defined on Object itself  However  because the function is an override  the definition of toString   from your class is used even when the class instance s true type is hidden behind polymorphism   Overloading is the action of defining multiple methods with the same name  but with different parameters  It is unrelated to either overriding or polymorphism

User · Answer

Polymorphism simply means  Many Forms    It does not REQUIRE inheritance to achieve   as interface implementation  which is not inheritance at all  serves polymorphic needs   Arguably  interface implementation serves polymorphic needs  Better  than inheritance   For example  would you create a super-class to describe all things that can fly   I should think not   You would be be best served to create an interface that describes flight and leave it at that   So  since interfaces describe behavior  and method names describe behavior  to the programmer   it is not too far of a stretch to consider method overloading as a lesser form of polymorphism

User · Answer

what is polymorphism    From java tutorial  The dictionary definition of polymorphism refers to a principle in biology in which an organism or species can have many different forms or stages  This principle can also be applied to object-oriented programming and languages like the Java language  Subclasses of a class can define their own unique behaviors and yet share some of the same functionality of the parent class   By considering the examples and definition  overriding should be accepted answer    Regarding your second query      IF you had a abstract base class that defined a method with no implementation  and you defined that method in the sub class  is that still overridding    It should be called overriding    Have a look at this example to understand different types of overriding     Base class provides no implementation and sub-class has to override complete method -  abstract  Base class provides default implementation and sub-class can change the behaviour Sub-class adds extension to base class implementation by calling super methodName   as first statement Base class defines structure of the algorithm  Template method  and sub-class will override a part of algorithm   code snippet   import java util HashMap   abstract class Game implements Runnable       protected boolean runGame   true      protected Player player1   null      protected Player player2   null      protected Player currentPlayer   null       public Game            player1   new Player  Player 1            player2   new Player  Player 2            currentPlayer   player1          initializeGame                  Type 1  Let subclass define own implementation  Base class defines abstract method to force         sub-classes to define implementation                 protected abstract void initializeGame            Type 2  Sub-class can change the behaviour  If not  base class behaviour is applicable        protected void logTimeBetweenMoves Player player           System out println  Base class  Move Duration  player PlayerActTime - player MoveShownTime                  Type 3  Base class provides implementation  Sub-class can enhance base class implementation by calling         super methodName   in first line of the child class method and specific implementation later        protected void logGameStatistics            System out println  Base class  logGameStatistics                  Type 4  Template method  Structure of base class can t be changed but sub-class can some part of behaviour        protected void runGame   throws Exception          System out println  Base class  Defining the flow for Game               while   runGame                               1  Set current player             2  Get Player Move                            validatePlayerMove currentPlayer                 logTimeBetweenMoves currentPlayer               Thread sleep 500               setNextPlayer                      logGameStatistics                 sub-part of the template method  which define child class behaviour        protected abstract void validatePlayerMove Player p        protected void setRunGame boolean status           this runGame   status            public void setCurrentPlayer Player p           this currentPlayer   p            public void setNextPlayer            if   currentPlayer    player1                currentPlayer   player2           else              currentPlayer   player1                      public void run            try              runGame             catch Exception err               err printStackTrace                       class Player      String name      Player String name           this name   name            public String getName            return name              Concrete Game implementation     class Chess extends Game      public Chess            super              public void initializeGame            System out println  Child class  Initialized Chess game              protected void validatePlayerMove Player p           System out println  Child class  Validate Chess move   p getName               protected void logGameStatistics            super logGameStatistics            System out println  Child class  Add Chess specific logGameStatistics             class TicTacToe extends Game      public TicTacToe            super              public void initializeGame            System out println  Child class  Initialized TicTacToe game              protected void validatePlayerMove Player p           System out println  Child class  Validate TicTacToe move   p getName              public class Polymorphism      public static void main String args             try               Game game   new Chess                Thread t1   new Thread game               t1 start                Thread sleep 1000               game setRunGame false               Thread sleep 1000                game   new TicTacToe                Thread t2   new Thread game               t2 start                Thread sleep 1000               game setRunGame false             catch Exception err               err printStackTrace                               output   Child class  Initialized Chess game Base class  Defining the flow for Game  Child class  Validate Chess move Player 1 Base class  Move Duration  player PlayerActTime - player MoveShownTime Child class  Validate Chess move Player 2 Base class  Move Duration  player PlayerActTime - player MoveShownTime Base class  logGameStatistics  Child class  Add Chess specific logGameStatistics  Child class  Initialized TicTacToe game Base class  Defining the flow for Game  Child class  Validate TicTacToe move Player 1 Base class  Move Duration  player PlayerActTime - player MoveShownTime Child class  Validate TicTacToe move Player 2 Base class  Move Duration  player PlayerActTime - player MoveShownTime Base class  logGameStatistics

User · Answer

Neither   Overloading is when you have the same function name that takes different parameters   Overriding is when a child class replaces a parent s method with one of its own  this in iteself does not constitute polymorphism    Polymorphism is late binding  e g  the base class  parent  methods are being called but not until runtime does the application know what the actual object is - it may be a child class whose methods are different   This is because any child class can be used where a base class is defined   In Java you see polymorphism a lot with the collections library   int countStuff List stuff      return stuff size        List is the base class  the compiler has no clue if you re counting a linked list  vector  array  or a custom list implementation  as long as it acts like a List   List myStuff   new MyTotallyAwesomeList    int result   countStuff myStuff     If you were overloading you d have   int countStuff LinkedList stuff        int countStuff ArrayList stuff        int countStuff MyTotallyAwesomeList stuff        etc      and the correct version of countStuff   would be picked by the compiler to match the parameters

User · Answer

The classic example  Dogs and cats are animals  animals have the method makeNoise  I can iterate through an array of animals calling makeNoise on them and expect that they would do there respective implementation   The calling code does not have to know what specific animal they are   Thats what I think of as polymorphism

User · Answer

Both overriding and overloading are used to achieve polymorphism    You could have a method in a class     that is overridden in one or     more subclasses  The method does     different things depending on which     class was used to instantiate an object       abstract class Beverage          boolean isAcceptableTemperature               class Coffee extends Beverage          boolean isAcceptableTemperature                 return temperature  gt  70                      class Wine extends Beverage          boolean isAcceptableTemperature                 return temperature  lt  10                   You could also have a method that is     overloaded with two or more sets of arguments  The method does     different things based on the     type s  of argument s  passed       class Server           public void pour  Coffee liquid                new Cup   fillToTopWith liquid                      public void pour  Wine liquid                new WineGlass   fillHalfwayWith liquid                      public void pour  Lemonade liquid  boolean ice                Glass glass   new Glass                if  ice                    glass fillToTopWith new Ice                               glass fillToTopWith liquid

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Polymorphism is the ability for an object to appear in multiple forms   This involves using inheritance and virtual functions to build a family of objects which can be interchanged   The base class contains the prototypes of the virtual functions  possibly unimplemented or with default implementations as the application dictates  and the various derived classes each implements them differently to affect different behaviors

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Polymorphism is more likely as far as it s meaning is concerned     to OVERRIDING in java  It s all about different behavior of the SAME object in different situations In programming way     you can call different ARGUMENTS    I think the example below will help you to understand     Though it s not PURE java code           public void See Friend                 System out println  Talk             But if we change the ARGUMENT     the BEHAVIOR will be changed           public void See Enemy                 System out println  Run             The Person here the  Object   is same

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The term overloading refers to having multiple versions of something with the same name  usually methods with different parameter lists  public int DoSomething int objectId          public int DoSomething string objectName            So these functions might do the same thing but you have the option to call it with an ID  or a name   Has nothing to do with inheritance  abstract classes  etc   Overriding usually refers to polymorphism  as you described in your question

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You are correct that overloading is not the answer   Neither is overriding   Overriding is the means by which you get polymorphism    Polymorphism is the ability for an object to vary behavior based on its type   This is best demonstrated when the caller of an object that exhibits polymorphism is unaware of what specific type the object is

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overloading is when you define 2 methods with the same name but different parameters  overriding is where you change the behavior of the base class via a function with the same name in a subclass   So Polymorphism is related to overriding but not really overloading   However if someone gave me a simple answer of  overriding  for the question  What is polymorphism   I would ask for further explanation

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Here s an example of polymorphism in pseudo-C  Java   class Animal       abstract string MakeNoise        class Cat   Animal       string MakeNoise              return  Meow            class Dog   Animal       string MakeNoise              return  Bark            Main         Animal animal   Zoo GetAnimal        Console WriteLine  animal MakeNoise          The Main function doesn t know the type of the animal and depends on a particular implementation s behavior of the MakeNoise   method   Edit  Looks like Brian beat me to the punch  Funny we used the same example  But the above code should help clarify the concepts

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I think guys your are mixing concepts  Polymorphism is the ability of an object to behave differently at run time  For achieving this  you need two requisites    Late Binding Inheritance    Having said that overloading means something different to overriding depending on the language you are using  For example in Java does not exist overriding but overloading  Overloaded methods with different signature to its base class are available in the subclass  Otherwise they would be overridden  please  see that I mean now the fact of there is no way to call your base class method from outside the object    However in C   that is not so  Any overloaded method  independently whether the signature is the same or  not  diffrrent amount  different type  is as well overridden  That is to day  the base class  method is no longer available in the subclass when being called from outside the subclass object  obviously   So the answer is when talking about Java use overloading  In any other language may be different as it happens in c

[java] Polymorphism vs Overriding vs Overloading

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