Is Constructor Overriding Possible

Question

What i know is  the compiler writes a default no argument constructor in the byte code  But if we write it ourselves  that constructor is called automatically  Is this phenomena a constructor overriding

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Your example is not an override  Overrides technically occur in a subclass  but in this example the contructor method is replaced in the original class

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Because a constructor cannot be inherited in Java and Method Overriding requires inheritance  Therefore  it s not applicable

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Cannot override constructor  Constructor can be regarded as static  subclass cannot override its super constructor   Of course  you could call protected-method in super class constructor  then overide it in subclass to change super class constructor  However  many persons suggest not to use the trick  in order to protect super class constructor behavior  For instance  FindBugs will warn you that a constructor calls a non-final method

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While others have pointed out it is not possible to override constructors syntactically  I would like to also point out  it would be conceptually bad to do so  Say the superclass is a dog object  and the subclass is a Husky object  The dog object has properties such as  quot 4 legs quot    quot sharp nose quot   if  quot override quot  means erasing dog and replacing it with Husky then Husky would be missing these properties and be a broken object  Husky never had those properties and simply inherited them from dog  On the other hand  if you intend to give Husky everything that dog has  then conceptually you could  quot override quot  dog with Husky  but there would be no point in creating a class that is the same as dog  it s not practically an inherited class but a complete replacement

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No it is not possible to override a constructor  If we try to do this then compiler error will come  And it is never possible in Java  Lets see the example  It will ask please write a return type o the method  means it will treat that overriden constructor as a method not as a constructor   package com sample test   class Animal       public static void showMessage                 System out println  we are in Animal class             class Dog extends Animal       public void DogShow                  System out println  we are in Dog show class                public static void showMessage                 System out println  we are in overriddn method of dog class             public class AnimalTest         public static void main String    args                Animal animal   new Animal            animal showMessage             Dog dog   new Dog            dog DogShow             Animal animal2   new Dog            animal2 showMessage

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Constructor overriding is not possible because of following reason   Constructor name must be the same name of class name  In Inheritance practice you need to create two classes with different names hence two constructors must have different names  So constructor overriding is not possible and that thought not even make sense

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What you describe isn t overriding  If you don t specify a default constructor  the compiler will create a default constructor  If it s a subclass  it will call  the default parent constructor super     it will also initialize all instance variables to a default value determined by the type s default value 0 for numeric types  false for booleans  or null for objects    Overriding happens when a subclass has the same name  number type of parameters  and the same return type as an instance method of the superclass  In this case  the subclass will override the superclass s method  Information on overriding here

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Constructors are not normal methods and they cannot be  overridden   Saying that a constructor can be overridden would imply that a superclass constructor would be visible and could be called to create an instance of a subclass  This isn t true    a subclass doesn t have any constructors by default  except a no-arg constructor if the class it extends has one   It has to explicitly declare any other constructors  and those constructors belong to it and not to its superclass  even if they take the same parameters that the superclass constructors take   The stuff you mention about default no arg constructors is just an aspect of how constructors work and has nothing to do with overriding

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But if we write it ourselves  that   constructor is called automatically    That s not correct  The no-args constructor is called if you call it  and regardless of whether or not you wrote it yourself  It is also called automatically if you don t code an explicit super      call in a derived class   None of this constitutes constructor overriding  There is no such thing in Java  There is constructor overloading  i e  providing different argument sets

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It should also be noted that you can t override the constructor in the subclass with the constructor of the superclass s name  The rule of OOPS tells that a constructor should have name as its class name  If we try to override the superclass constructor it will be seen as an unknown method without a return type

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It is never possible  Constructor Overriding is never possible in Java      This is because       Constructor looks like a method but   name should be as class name and no   return value       Overriding means what we have declared   in Super class  that exactly we have   to declare in Sub class it is called   Overriding  Super class name and Sub   class names are different       If you trying to write Super class   Constructor in Sub class  then Sub   class will treat that as a method not   constructor because name should   not match with Sub class name  And it   will give an compilation error that   methods does not have return value  So   we should declare as void  then only   it will compile        Have a look at the following code      Class One                                  One        Super Class constructor                                    One int a       Super Class Constructor Overloading                               Class Two extends One                                          One           this is a method not constructor                                    because name should not match with Class name                                           Two        sub class constructor                                                                    Two int b       sub class constructor overloading

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Constructor looks like a method but name should be as class name and no return value   Overriding means what we have declared in Super class  that exactly we have to declare in Sub class it is called Overriding  Super class name and Sub class names are different   If you trying to write Super class Constructor in Sub class  then Sub class will treat that as a method not constructor because name should not match with Sub class name  And it will give an compilation error that methods does not have return value  So we should declare as void  then only it will compile

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I found this as a good example for this question      class Publication        private String title       public Publication String title            this title   title             public String getDetails             return  quot title   quot  quot    title    quot   quot  quot             class Newspaper extends Publication        private String source       public Newspaper String title  String source            super title           this source   source              Override     public String getDetails             return super getDetails      quot   source   quot  quot    source    quot   quot  quot            class Article extends Publication        private String author       public Article String title  String author            super title           this author   author              Override     public String getDetails             return super getDetails      quot   author   quot  quot    author    quot   quot  quot             class Announcement extends Publication        private int daysToExpire       public Announcement String title  int daysToExpire            super title           this daysToExpire   daysToExpire              Override     public String getDetails             return super getDetails      quot   daysToExpire  quot    daysToExpire

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method overriding in java is used to improve the recent code performance written previously    some code like shows that here we are creating reference of base class and creating phyisical instance of the derived class  in constructors overloading is possible   InputStream fis new FileInputStream  a txt    int size fis available      size will return the total number of bytes possible in a txt so

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You can have many constructors as long as they take in different parameters   But the compiler putting a default constructor in is not called  constructor overriding

[java] Is Constructor Overriding Possible?

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