Apex Developer Guide

Apex Developer Guide
Release Notes
Getting Started with Apex
Introducing Apex
What is Apex?
Understanding Apex Core Concepts
When Should I Use Apex?
How Does Apex Work?
Developing Code in the Cloud
Apex Development Process
Apex Quick Start
Writing Apex
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.

Developing Code in the Cloud

The Apex programming language is saved and runs in the cloud—the multitenant platform. Apex is tailored for data access and data manipulation on the platform, and it enables you to add custom business logic to system events. While it provides many benefits for automating business processes on the platform, it is not a general purpose programming language.
Apex cannot be used to:
  • Render elements in the user interface other than error messages
  • Change standard functionality—Apex can only prevent the functionality from happening, or add additional functionality
  • Create temporary files
  • Spawn threads

All Apex code runs on the Lightning Platform, which is a shared resource used by all other organizations. To guarantee consistent performance and scalability, the execution of Apex is bound by governor limits that ensure no single Apex execution impacts the overall service of Salesforce. This means all Apex code is limited by the number of operations (such as DML or SOQL) that it can perform within one process.

All Apex requests return a collection that contains from 1 to 50,000 records. You cannot assume that your code only works on a single record at a time. Therefore, you must implement programming patterns that take bulk processing into account. If you don’t, you may run into the governor limits.

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