- Encapsulation links data with the code that manipulates it.
- Encapsulation provides another important attribute called access control.
- Java’s access specifiers are public, private, and protected.
- A default access level is also defined in Java.
- protected applies only during inheritance.
- When a member of a class is declared as public, then that member can be accessed by any other code.
- When a member of a class is declared as private, then that member can only be accessed by other members of its class.
- When no access specifier is used, then by default the member of a class is public within its own package, but cannot be accessed outside of
- its package.
- main( ) method in Java is declared as public because it is called by code that is outside the program—that is, by the Java run-time system.
- The methods that are declared but not implemented are called abstract methods.
- An abstract class can contain abstract methods and fully implemented methods both.
- All of the methods in an interface are implicitly abstract, so the
abstract modifier is not used with interface methods.
- If an abstract class contains only abstract method declarations, it should be declared as an interface instead.
- Unlike interfaces, abstract classes can contain fields that are not
final, and they can contain implemented methods.