1. What is Apex?
Apex is a programming language created by Salesforce for customizing the Salesforce platform.
2. Different types of collections in Apex?
Apex supports Lists, Sets, and Maps as collection types.
3. Tell me the difference between a List and a Set in Apex?
A List is an ordered collection that permits duplicates; a Set is unordered and does not allow duplicates.
4. What is a trigger in Apex?
A trigger is an Apex script that executes before or after DML events like insert, update, and delete.
5. Why use the “with sharing” keyword in Apex class definition?
The “with sharing” keyword enforces user-specific sharing rules.
6. What is a governor limit in Apex?
Governor limits are restrictions set by Salesforce to ensure efficient and secure Apex code execution.
7. Name a few types of governor limits in Salesforce.
Governor limits include restrictions on queries, DML operations, CPU usage, heap size, and callouts.
8. How can you handle exceptions in Apex?
Use try-catch blocks to handle exceptions, applying error-handling logic in catch blocks.
9. What is the difference between a Trigger and a Process Builder in Salesforce?
A trigger is an Apex script for DML events; Process Builder is a no-code automation tool.
10. How do you prevent hitting governor limits in your code?
Optimize code, employ bulk processing, and follow best practices; monitor limits during development.
11. What is the @AuraEnabled annotation used for?
The @AuraEnabled annotation allows methods to be called from Lightning Components.
12. How can you make a class or method globally accessible in Apex?
Use the “global” access modifier for accessibility outside your application or namespace.
13. Explain the difference between Trigger.old and Trigger.new in a trigger context.
Trigger.old holds records’ previous versions; Trigger.new holds records’ updated versions.
14. What is the purpose of using the “Test” class in Apex?
The “Test” class is for writing test methods to validate Apex code functionality.
15. How do you perform a callout to an external service in Apex?
Perform callouts using Apex’s HTTP classes like Http and HttpRequest.
16. What is a Batch Apex class?
Batch Apex processes data in smaller chunks to avoid governor limit issues.
17. How can you implement a singleton pattern in Apex?
Use a private constructor and a static instance variable in the class.
18. Explain the difference between a before trigger and an after trigger.
A before trigger executes before database saving; an after trigger executes after saving.
19. What is the purpose of using the “Database” class in Apex?
The “Database” class offers methods for DML operations, like insert, update, delete, and upsert.
20. How can you schedule an Apex class to run at a specific time?
Use the Salesforce scheduler and “Scheduler” class to run a class at a set time.
21. What is a future method in Apex?
A future method performs asynchronous processing, marked with the “@future” keyword.
22. How can you prevent recursive triggers in Apex?
Prevent recursion by using a static variable or static set to track trigger execution.
23. What is the purpose of the “Limits” class in Apex?
The “Limits” class provides methods to access information about current execution’s governor limits.
24. What is the difference between a PageReference and a PageReference object in Apex?
A PageReference navigates to a Visualforce page; a PageReference object manipulates URLs in Apex.
25. How can you debug Apex code in Salesforce?
Use System.debug() for logging, employ the Developer Console, or configure Debug Logs in Setup.