Class 37: Dictionaries (1): Implementing Dictionaries with Vectors

Held: Monday, April 10, 2006

Summary: Today we begin t consider of a new abstract data type, the Dictionary. Dictionaries provide indexed access to values in which the indices may be a variety of objects (most typically strings).

Related Pages:

• EBoard.
• TAO of Java: Dictionaries.
• TAO of Java: Laboratory: A Simple Dictionary Implementation.

Notes:

• Questions on the exam?
• Guest speaker tomorrow.

Overview:

• Introduction to dictionaries.
• Lab.

An Introduction to Dictionaries

• In our investigation of vectors and arrays, we've seen structures that collect objects in which the objects can be indexed by numbers.
• Are there other ways to index collections? Yes, we could index collections by strings.
• We could also index by other objects (Strings, Integers, Points, whatever).
• Collections of objects indexed by objects are called dictionaries.
  • Some people also refer to them as keyed tables.
  • Other people refer to them as maps
• Some more terminology:
  • The objects we're using as indices are called keys.
  • The objects we're looking up are called values.

Laboratory

• Attempt the lab.