Apex Developer Guide

Apex Developer Guide
Release Notes
Getting Started with Apex
Writing Apex
Data Types and Variables
Control Flow Statements
Classes, Objects, and Interfaces
Classes
Interfaces
Keywords
Annotations
Classes and Casting
Classes and Collections
Collection Casting
Differences Between Apex Classes and Java Classes
Class Definition Creation
Namespace Prefix
Apex Code Versions
Lists of Custom Types and Sorting
Using Custom Types in Map Keys and Sets
Working with Data in Apex
Document Your Apex Code
Running Apex
Debugging, Testing, and Deploying Apex
Apex Reference
Appendices
PDF

Note: This release is in preview. Features described here don’t become generally available until the latest general availability date that Salesforce announces for this release. Before then, and where features are noted as beta, pilot, or developer preview, we can’t guarantee general availability within any particular time frame or at all. Make your purchase decisions only on the basis of generally available products and features.

Classes and Collections

Lists and maps can be used with classes and interfaces, in the same ways that lists and maps can be used with sObjects. This means, for example, that you can use a user-defined data type for the value or the key of a map. Likewise, you can create a set of user-defined objects.

If you create a map or list of interfaces, any child type of the interface can be put into that collection. For instance, if the List contains an interface i1, and MyC implements i1, then MyC can be placed in the list.