Abstract Class

Abstract Class

1. Class could be abstract even if its superclass is concrete

2. Abstract Methods

   • could exist only inside of abstract classes
   • nonstatic

3. Constructors

   • must be declared as protected
     • used only by subclasses
   • it is impossible to create instances of an abstract class

4. Subclasses

   • must implement all abstract methods declared in the abstract class
     • otherwise it becomes an abstract class
   • Extends <Abstract class>

5. Can be used as data type

6. Could exist without any abstract method