Please give me roadmap to learn APEX and it's best practices.

Hi @Hitesh Sharma 

If you're completely new to Apex, I would recommend learning it step by step rather than trying to learn everything at once.

A good learning path is:

1. Programming fundamentals

• Variables and data types
• If/else and switch
• Loops
• Methods
• Classes and objects
• Collections: List, Set, Map

2. Salesforce fundamentals

• sObjects
• Object relationships
• SOQL
• SOSL
• DML
• Database methods
• Exception handling

Salesforce's Apex Basics & Database module is a good starting point. Apex Basics & Database — Trailhead

For SOQL, this is particularly useful: SOQL Queries in Apex — Trailhead

3. Apex classes

Learn how to build reusable classes and methods. Then understand:

• public, private, protected
• static
• Constructors
• Interfaces
• Inheritance
• Encapsulation

4. Triggers

After you are comfortable with classes, SOQL and DML, learn triggers.

Focus on:

• Trigger context variables
• Before vs after triggers
• Trigger handler pattern
• Bulkification
• Recursion control
• Moving business logic into classes

Salesforce recommends understanding Apex basics, SOQL and database concepts before triggers.

5. Governor Limits & Bulkification — VERY IMPORTANT

This is one of the biggest differences between normal programming and Salesforce development.

Always remember:

❌ Don't put SOQL inside a loop 

❌ Don't put DML inside a loop

Instead:

List<Account> accounts = [
    SELECT Id, Name
    FROM Account
    WHERE Id IN :accountIds
];
update accounts;

Learn to design your code for 1 record and 200 records from the beginning. Salesforce specifically recommends bulk operations to avoid governor-limit problems.

6. Apex Testing

Learn:

• @IsTest
• Test data creation
• Test.startTest()
• Test.stopTest()
• System.assert
• Positive/negative tests
• Bulk tests
• Testing exceptions
• Mock callouts

Don't write tests just to achieve 75% coverage. Test the actual business requirements and edge cases. Salesforce currently requires at least 75% Apex coverage for deployment, with every trigger having coverage.

7. Asynchronous Apex

Then move to:

• Queueable Apex
• Batch Apex
• Scheduled Apex
• Future methods

Understand when and why to use each one rather than just memorizing syntax.

8. Integration

Finally learn:

• HTTP callouts
• REST APIs
• JSON
• Named Credentials
• External Credentials
• Apex REST
• Authentication
• Callout testing with mocks

Recommended order

Programming Basics → Collections → sObjects → SOQL → DML → Classes → Exception Handling → Governor Limits → Bulkification → Triggers → Testing → Queueable → Batch → Scheduled Apex → REST/Callouts → Architecture

I would follow roughly 30% theory + 70% hands-on practice.

For example, don't just read about SOQL. Create Accounts, Contacts and Opportunities and write 20–30 queries yourself.

Official resources

• Apex Developer Guide — Salesforce — comprehensive reference covering Apex fundamentals, testing, governor limits, triggers, asynchronous Apex and more.
• Apex Basics & Database — Trailhead
• Apex Triggers — Trailhead
• Apex Testing — Trailhead
• Asynchronous Apex — Trailhead
• Apex Integration Services — Trailhead

Most importantly, build small projects while learning. For example: build an Opportunity management class → add a trigger → bulkify it → write test classes → add Queueable processing → expose functionality through a REST API.

That will teach you much faster than reading Apex syntax alone.