What are differences between Interface and Abstract class
Answer: Please see all differences below:
Interface | Abstract Class |
| By default all methods are abstract when you define interface and cannot have define its implementation | But in abstract class you could define instance method with default implementation |
| Only public, static & final are permitted modifiers variables are permitted | All modifiers are permitted for variables |
| Interface can be implemented using key word “Implements” | Abstracts class can be extend using key word “extends” |
| By default variables in interface are final | Abstract class can contain non final variables |
| Members of interface are public by default | But in Abstract class you could use others modifiers as well like private, public or protected |
| A java class can implements multiple interface | But java class can only extends one Abstract class |
| Interface definition completely abstract and cannot be instantiated | Yes, Abstract class also cannot be instantiated but could be invoked if main method avaialable. |
