Unit 5 - Collections, Lists, Maps, Roles of Types

Question 1

In principle, there are two different approaches how types and values can be linked:

Answer 1

1. Types intrinsic to values: A type owned by a value. A value has a unique type.
2. Types as value classifiers: Types are patterns describing a range of values. For each
   classifying type, each value either is or is not conforming to this type. A value can
   conform to several such types.

Question 2

Values have intrinsic types to facilitate

Answer 2

dynamic checking and inspection.

Question 3

Variables, method parameters and method return values (or other value holders) have

Answer 3

classifying types so that only certain values can be associated with them.

Question 4

A collection is a

Answer 4

composite value that holds a number of component values that can be easily added, removed or changed.

Question 5

Collections can be categorised two criteria

Answer 5

as homogeneous vs heterogeneous

and as

fixed-size vs dynamic

Question 6

Homogeneous, also known as uniform, collections are those

Answer 6

where all elements in each collection have the same type.

Question 7

Heterogeneous collections are those

Answer 7

where one can mix values of different types in one collection. The values may conform to a classifying type that permits a wide variety of intrinsic types.

Question 8

Examples of fixed-size collections are Java…

Answer 8

arrays

Question 9

Examples of dynamic collections are Java…

Answer 9

lists, sets and maps.

Question 10

Collections are further classified by the kind of abstract structure that holds the components together:

Answer 10

• Sequences
• Maps
• Sets

Question 11

Collections are further classified by the kind of abstract structure that holds the components together:

Sequences

Answer 11

Components form a linear structure that can be used to refer to particular components (eg 101st component), and can be altered by explicit instructions (eg insert an element at the back of a list).

Question 12

Collections are further classified by the kind of abstract structure that holds the components together:

Maps

Answer 12

(also known as dictionaries): Components are stored with unique keys by which they can be identified within the collection. The keys can be of almost any type. When the keys are integers in a range 1 . . . n or 0 . . . (n − 1), the map becomes a sequence.

Question 13

Collections are further classified by the kind of abstract structure that holds the components together:

Sets

Answer 13

No structure visible to programmer, a component is either there or not and no information is accessible about its position in the set.

Question 14

N/a

Answer 14

Done up to 5.3 Pg4