concrete class, abstract class and interface in java
- concrete class
- contain only concrete method
- can instance objects
- have constructor
- support only single inheritance
- inheritance from (concrete class or and abstract class)
- Abstract class
- contain both concrete method and abstract method
- use keyword “abstract class”
- cannot instance object
- have constructor
- can also have 100% concrete method
- interface
- completely abstract
- all method must be abstract
- use keyword “interface”
- support multi Inheritance ( interface extended many interfaces)
- cannot have constructor
- cannot instance object
- all data member must be “public static”
