how to inherit Constructor from super class to sub class

Question

How to inherit the constructor from a super class to a sub class

User · Answer

Read about the super keyword  Scroll down the Subclass Constructors   If I understand your question  you probably want to call a superclass constructor   It is worth noting that the Java compiler will automatically put in a no-arg constructor call to the superclass if you do not explicitly invoke a superclass constructor

User · Answer

Say if you have               public KKSSocket final KKSApp app  final String name        this app   app      this name   name              then a sub-class named KKSUDPSocket extending KKSSocket could have           param app     param path     param remoteAddr     public KKSUDPSocket KKSApp app  String path  KKSAddress remoteAddr        super app  path  remoteAddr       and          param app     param path     public KKSUDPSocket KKSApp app  String path        super app  path       You simply pass the arguments up the constructor chain  like method calls to super classes  but using super      which references the super-class constructor and passes in the given args

User · Answer

You inherit class attributes  not class constructors  This is how it goes    If  no constructor is added in the super class  if no then the compiler adds a no argument contructor  This default constructor is invoked implicitly whenever a new instance of the sub class is created   Here the sub class may or may not have constructor  all is ok    if a constructor is provided in the super class  the compiler will  see if it is a no arg constructor or a constructor with parameters   if no args  then the compiler will invoke it for any sub class instanciation   Here also the sub class may or may not have constructor  all is ok    if 1 or more contructors in the parent class have parameters and no args constructor is absent  then the subclass has to have at least 1 constructor where an implicit call for the parent class construct is made via super  parent contractor params     this way you are sure that the inherited class attributes are always instanciated

User · Answer

Superclass constructor CAN T be inherited in extended class  Although it can be invoked in extended class constructor s with super   as the first statement

User · Answer

Constructors are not inherited  you must create a new  identically prototyped constructor in the subclass that maps to its matching constructor in the superclass   Here is an example of how this works   class Foo       Foo String str         class Bar extends Foo       Bar String str               Here I am explicitly calling the superclass             constructor - since constructors are not inherited            you must chain them like this          super str

User · Answer

Default constructors -- public constructors with out arguments  either declared or implied  -- are inherited by default   You can try the following code for an example of this   public class CtorTest       public static void main String   args            final Sub sub   new Sub            System err println  Finished                private static class Base           public Base                 System err println  In Base ctor                         private static class Sub extends Base           public Sub                 System err println  In Sub ctor                        If you want to explicitly call a constructor from a super class  you need to do something like this   public class Ctor2Test       public static void main String   args            final Sub sub   new Sub            System err println  Finished                private static class Base           public Base                 System err println  In Base ctor                       public Base final String toPrint                System err println  In Base ctor   To Print      toPrint                        private static class Sub extends Base           public Sub                 super  Hello World                 System err println  In Sub ctor                        The only caveat is that the super   call must come as the first line of your constructor  else the compiler will get mad at you

[java] how to inherit Constructor from super class to sub class

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