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
Differences Between Apex Classes and Java Classes
Class Definition Creation
Namespace Prefix
Apex Code Versions
Setting the Salesforce API Version for Classes and Triggers
Setting Package Versions for Apex Classes and Triggers
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

Apex Code Versions

To aid backwards-compatibility, classes and triggers are stored with the version settings for a specific Salesforce API version.

If an Apex class or trigger references components, such as a custom object, in installed managed packages, the version settings for each managed package referenced by the class are saved too. This ensures that as Apex, the API, and the components in managed packages evolve in subsequent released versions, a class or trigger is still bound to versions with specific, known behavior.

Setting a version for an installed package determines the exposed interface of any Apex code in the installed package. This allows you to continue to reference Apex that may be deprecated in the latest version of an installed package, if you installed a version of the package before the code was deprecated.

Typically, you reference the latest Salesforce API version and each installed package version. If you save an Apex class or trigger without specifying the Salesforce API version, the class or trigger is associated with the latest installed version by default. If you save or redeploy an Apex class or trigger that references a managed package without specifying a version of the managed package, the class or trigger is associated with the latest installed version of the managed package by default.

Versioning of Apex Classes and Methods

When classes and methods are added to the Apex language, those classes and methods are available to all API versions your Apex code is saved with, regardless of the API version (Salesforce release) they were introduced in. For example, if a method was added in API version 33.0, you can use this method in a custom class saved with API version 33.0 or another class saved with API version 25.0.

There is one exception to this rule. The classes and methods of the ConnectApi namespace are supported only in the API versions specified in the documentation. For example, if a class or method is introduced in API version 33.0, it is not available in earlier versions. For more information, see ConnectApi Versioning and Equality Checking.

Keep these guidelines in mind regarding API version usage:

  • Salesforce strongly recommends that you use the latest available API version.
  • If you can't upgrade to the latest version yet, use API versions released in the past three years, for improved performance, security, and compatibility.
  • To reduce complexity, consolidate your Apex codebase to use the minimal number of API versions, ideally, just one API version.

For a non-exhaustive list of major Apex behavior changes across API versions, organized by version number, see Apex Versioned Behavior Changes.