[Solved] Understanding assignments and “extends” in Java

by 


extends

is used for inheritance and in layman term it resembles “is-a” property

So class A which extends some other class B, means that “Class A is-a Class B”.
And in other words Class B is a Parent of Class A.

Parent class reference can hold a child object but vice-versa is not possible.

Cell c = new BloodCell();   // OK, as BloodCell is a Cell,
Cell c = new RedBloodCell();   // OK, RedBloodCell is a Cell
BloodCell c = new RedBloodCell();   // OK, RedBloodCell is a BloodCell
RedBloodCell c = new BloodCell();  // ERROR, BloodCell is not a RedBloodCell

1

solved Understanding assignments and “extends” in Java