Interface:
- Interface allow to define only abstract methods.
- Interface methods are ‘public abstract’ by default.
| interface Sample { void m1(); void m2(); } |
implements:
- ‘implements’ is a keyword.
- Interface must ‘implements’ by class.
- Implemented class override all abstract methods of an interface.
| interface First { void m1(); void m2(); } class Second implements First { public void m1(){ System.out.println(“m1….”); } public void m2(){ System.out.println(“m2….”); } } class Main { public static void main(String[] args){ First obj = new Second(); obj.m1(); obj.m2(); } } |
| Upcasting: object reference of implemented class storing into Interface type variable |
Relations:
