7: There are 3 kinds of inheritance

  1.   Multilevel inheritance (JAVA supports)

  2.   Multiple inheritance(C,C++  supports,JAVA does not)

   3.   Cyclic inheritance(no programming language).

Program for Multilevel inheritance:

class GrandFather {                  // parent class (or)  super class  int age ; void  cultivator( )   { System.out.println("my grand fa was a cultivator");    }    } class Father  extends  GrandFather   {              // Father sub class int age ; void  cultivator( )   { System.out.println("Father was cultivator");     } void  business( )   { System.out.println("Father was a businessMan");  }} //Son is Sub Class here and Father is a superclass class Son extends Father   { int age ; void  teacher( )   { System.out.println("Teacher");   } void cultivator( )   { System.out.println("Son is cultivator"); super.cultivator();    } void  business( )   { System.out.println("Son is a businessMan");   } public static void main(String[] args)   { Son son = new Son(); son.cultivator();     }   }                         //class Son extends GrandFather, Father // not possible in java.

Explanation:-

Ø Son son = new Son();

Ø Object will be created for Son class variable son.

Ø Son();will be executed constructor of Son class will be loaded.

Ø Compiler will do following for us

class Son extends Father   { Son( )    { Super( );     .}    }                        //this is a call to super class constructor class Father extends GrandFather   { Father ( )    { Super ( );               .}   }                          //jvm will checks extends any other class class GrandFather   {                               // super class  GrandFather( )   { //since this class is not extending any other class compiler will not create any super(); }      }

Multiple inheritance:-

Explanation:-

Ø Inside the Son class if we say super.cultivator();

Ø JVM will not understands which method has  to be executed.it leads ambiguity.which will become a complexity in JAVA.Son class have two super classes.

Ø So,JAVA will not supports multiple inheritance.

Note:-        1.multiple inheritance and pointers leads confusion.so,they are removed in JAVA.

1.   In C++  multiple inheritance is supported by using friend functions.

Cyclic inheritance:-

So,cyclic inheritance will not supported any programming language.

Java.lang.Object  :-      “Object” is a class which is a super class to all the classes in JAVA.

Eg:-    class A  {                             //stmts                    }

Compiler:    It will checks if A is extending any other class.

                    If yes it will checks that, otherwise it will extends Object class.

Fig:-multilevel inheritance object creation

Method overriding:-

Process of defining a method with same name,same signature in sub class for a method already exist in its super class.

We can override methods of supermost classes also.

We can have 5 classes we can inheritance hierarchy as follows

According java coding standards the      hierarchy is limited to 5 classes.    Eg:-

class Addition   { int sum(int i, int j)   { int  total = i+j ; return total ;               }    } class ChildAddition extends Addition  { int sum(int a, int b)   { int total = a+b+100 ; return total ;                  } public void static main(String args[])   { ChildAddition      childAdd = new ChildAddition (); int tot = childAdd.sum(7,8); System.out.println(tot);               }    }

Super class referring sub class object rule:-

We can assign a sub class object into a super class reference.

Here for super class reference we can assign only super class non static contents.

Program same as above

public void static main(String args[])    {

Addition add=new ChildAddition();

Addition add=new Addition();     }