Core Java 10: Optionals, Tiers, Layers, Custom Objects, Sorted Collections

Question 1

Optional

Answer 1

wrapper class used as a return type for methods

Question 2

Why are optionals useful?

Answer 2

Optionals are used for communication; Optional is a wrapper class representing that a method returns null to represent a lack of a value

Question 3

Layer

Answer 3

a layer is a group of components that are reusable in similar circumstances

Question 4

Tier

Answer 4

a group of layers; examples include data tier, client tier, middle tier, business tier, etc.

Question 5

Collection

Answer 5

an iterable group of objects bound together by a DSA (List, Queue, or Set), as distinguishable from a Map

Question 6

How do you set up sorting of custom objects in java?

Answer 6

Use Collections.sort() method; to do this, need to create a comparator and pass it as an argument to Collections.sort()

Question 7

What is a sorted collection?

Answer 7

a sorted collection uses the Collections.sort() method (and usually a custom comparator object) to sort the collection in a specialized way.