Enterprise Systems Programming Fundamentals: Data Structures II - Lecture 5

Collections in Apex

• Composite data types that aggregate multiple types into a single variable.
• Three main types: Lists, Sets, and Maps.

Lists

• Ordered collection of elements of the same type.
• Elements can be of any data type (primitive, collections, custom).
• Lists resize dynamically.
• Syntax: List<Type> listName = new List<Type>();
• Access and modify elements using square brackets [] (zero-indexed).
• Common methods: add(), get(), size(), remove(), sort().
• Nested lists allow hierarchical data representation.

Sets

• Unordered collection of unique elements.
• Useful for ensuring no duplicates.
• Elements can be of any data type.
• Cannot directly access elements using an index.
• Syntax: Set<Type> setName = new Set<Type>();
• Methods: add(), addAll(), contains(), remove(), size().

Maps

• Collection of key-value pairs where each key is unique.
• Keys and values can be of any data type.
• Syntax: Map<KeyType, ValueType> mapName = new Map<KeyType, ValueType>();
• Methods: put(), get(), containsKey(), keySet(), values(), remove(), size().
• Keys are generally case-sensitive.

Apex vs Salesforce Field Data Types

• Apex data types are used within the programming language.
• Salesforce field data types define the structure and constraints of data stored within Salesforce object fields.