Object Oriented Programming - JAVA- Casting

Object Oriented Programming - JAVA👽

Casting ......

We use casting to catch a class using another class. So in this blog we discuss about Casting.
 
  
What's going on in Casting  ? In casting, we have to inherit classes.
Let's see an example.
    int x  = 5 ;    Integer variables have 32 bits.
   long y = 6 ;    Long variables have 64 bits.
       x = y ; ✖    We can't catch long variable using integer variable.
   y = x ; ✔    We can catch integer variable using long variable.

There are two types of casting.
  • Upcasting
  • Downcasting

Upcasting

    Upcasting is a process of assign subclass object to superclass variable that is reference of superclass. 

class Parent {
    //code
}
class Child extends Parent {
    //code
}
class Test {
    Parent p = new Child();
}
The object always runs in the class where the object is created. So, in upcasting, always run the subclass.

Downcasting

    Downcasting is a process of converting subclass object assigned to a variable with a subclass reference back into a subclass variable.

class Parent {
    //code
}
class Child extends Parent {
    //code
}
class Test {
    Parent p = new Child();
    Child c = (Child) p ;
}

We can downcasting only when we done upcasting process. 

See you in the next blog to discuss about Polymorphism.


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