Complete Java SE 8 Developer Bootcamp - Interfaces: Part 2

The video tutorial explains the concept of interfaces in Java, highlighting their role as contracts that define expected behaviors for implementing classes. It covers how classes can implement multiple interfaces, the importance of overriding methods, and the use of UML diagrams to understand class hierarchies. The tutorial also discusses abstract classes, default methods introduced in Java 8 for backward compatibility, and static methods, emphasizing their differences and usage.

What is the primary purpose of an interface in Java?

• To create instances of objects

• To allow multiple inheritance

• To provide default implementations

• To define a contract for implementing classes

Which keyword is used to implement an interface in a class?

• inherits

• extends

• implements

• uses

What happens if a class does not override an abstract method from an interface it implements?

• The method will be ignored

• The compilation will fail

• The class will become abstract

• The class will compile successfully

How does an abstract class differ from a concrete class in terms of method implementation?

• Abstract classes must implement all methods

• Abstract classes can choose not to implement methods

• Concrete classes cannot override methods

• Concrete classes must be final

What is a key feature of interfaces extending other interfaces?

• They cannot be used in class hierarchies

• They cannot have any methods

• They inherit methods from the extended interface

• They must be implemented separately

What is the purpose of a default method in an interface?

• To provide a mandatory implementation

• To allow interfaces to have instance variables

• To offer a default implementation without breaking existing code

• To enforce method overriding

Why can't default methods access instance variables?

• They are not allowed in interfaces

• They are static by nature

• Interfaces only have constants

• They are abstract

How are static methods in interfaces different from default methods?

• Static methods are accessed using the interface name

• Static methods are inherited by implementing classes

• Static methods can be overridden

• Static methods can access instance variables

What is the rule about overriding static methods?

• They can be overridden like instance methods

• They can only be hidden, not overridden

• They must be final

• They are always abstract

How do you access a static method defined in an interface?

• By using the method name directly

• By using the interface name

• By using the class name

• By creating an instance of the interface