What Is Salesforce Apex? Complete Developer Guide 2025
Salesforce Apex is a proprietary, Java-like programming language developed by Salesforce. It runs natively on the Salesforce platform and allows developers to build custom business logic, triggers, and integrations that go beyond what declarative tools like Flow can handle.
Apex Basics: What It Looks Like
// A simple Apex class
public class AccountHelper {
public static void updateAccountNames(List<Account> accounts) {
for (Account acc : accounts) {
acc.Name = acc.Name + ' - Updated';
}
update accounts;
}
}
If you’ve used Java or C#, Apex will feel familiar. It’s strongly typed, object-oriented, and runs in a multi-tenant cloud environment.
What Makes Apex Different (Governor Limits)
The most unique aspect of Apex is Governor Limits — enforced limits on resources per transaction to ensure no single tenant monopolizes shared infrastructure.
- Maximum SOQL queries per transaction: 100
- Maximum DML statements per transaction: 150
- Maximum records retrieved by SOQL: 50,000
- Maximum heap size: 6 MB (synchronous), 12 MB (async)
Breaking these limits causes a LimitException. All Apex code must be written “bulkified” — designed to handle collections of records, never one at a time.
Types of Apex You Need to Know
- Apex Triggers: Execute before/after record DML operations
- Apex Classes: Reusable business logic units
- @future Methods: Async methods for callouts and long-running operations
- Queueable Apex: Async processing with chaining capability
- Batch Apex: Processing millions of records in chunks
- Schedulable Apex: Time-based execution (like a cron job)
Apex Test Classes
All Apex must have at least 75% test coverage to deploy to production. Tests must use @isTest annotation and include System.assert() statements that verify expected behavior — not just reach coverage.
How to Start Learning Apex
- Have a Salesforce Developer Edition org (free at developer.salesforce.com)
- Complete “Apex Basics & Database” Trailhead module
- Complete “Apex Triggers” Trailhead module
- Practice writing triggers that handle bulk records from the start
- Prepare for PD1 exam with Dumpsforce PD1 practice questions
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