Apex is a powerful, object-oriented programming language used by developers to execute and manage complex business logic within the Salesforce platform. As the backbone of Salesforce development, mastering Apex is essential for developers looking to work within the Salesforce ecosystem. Whether you are an experienced developer or a beginner, preparing for an interview can be challenging, especially when it comes to technical roles like Apex developers.
In this article, we will cover the Top 36 Apex Interview Questions that you are likely to encounter in your next job interview. These questions range from basic to advanced, ensuring that you are fully prepared for whatever comes your way.
Top 36 Apex Interview Questions
1. What is Apex in Salesforce?
Apex is a strongly-typed, object-oriented programming language designed by Salesforce for building complex business logic, controlling workflow automation, and integrating external applications within the Salesforce platform. It is similar to Java and supports features like database manipulation and web service callouts.
Explanation:
Apex enables developers to execute custom logic on the Salesforce platform. It provides built-in support for transactions, rollbacks, and batch processing.
2. What are the main features of Apex?
Apex includes several key features, such as multitenancy support, automatic upgradeability, tight integration with Salesforce data, easy testing and debugging, support for web services, and built-in security features like governor limits to manage resource usage.
Explanation:
These features allow developers to write efficient, scalable code that integrates seamlessly with Salesforce’s core architecture.
3. What are governor limits in Apex?
Governor limits in Apex are restrictions that Salesforce enforces to ensure that shared resources are used efficiently in a multitenant environment. These limits include restrictions on database queries, DML statements, and CPU time usage per transaction.
Explanation:
Governor limits are in place to ensure fair use of Salesforce resources and to prevent excessive consumption of shared resources that could impact other tenants.
4. What is the difference between Apex Class and Apex Trigger?
An Apex class is a template or blueprint for creating objects in Salesforce, while an Apex trigger is used to perform operations when specific events occur in Salesforce, such as before or after data manipulation (insert, update, delete).
Explanation:
Apex classes are used to define custom logic, whereas Apex triggers allow developers to execute that logic in response to DML events.
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5. What is a SOQL query?
SOQL (Salesforce Object Query Language) is a query language similar to SQL used to fetch data from Salesforce objects. It is used to retrieve specific fields from a Salesforce object based on certain conditions or filters.
Explanation:
SOQL is optimized for querying Salesforce records and supports filtering, sorting, and aggregating data across multiple objects.
6. Can you explain the difference between SOQL and SOSL?
SOQL is used for querying one object or related objects in Salesforce, while SOSL (Salesforce Object Search Language) is used to search text across multiple objects simultaneously. SOSL is useful for full-text searches.
Explanation:
SOQL is similar to SQL in that it queries structured data, while SOSL performs text-based searches across multiple objects for broader retrieval.
7. What is a future method in Apex?
A future method in Apex allows for asynchronous execution of long-running operations that can be processed in the background. It is typically used for callouts to external services, complex calculations, or database operations that do not require immediate response.
Explanation:
Future methods help improve system performance by running resource-intensive operations asynchronously, freeing up the current transaction to complete quickly.
8. What is the @isTest annotation in Apex?
The @isTest annotation marks a class or method as a test class or test method in Apex. Test classes are used to validate the correctness of code and ensure it meets functional requirements. It is mandatory to achieve code coverage before deploying Apex to production.
Explanation:
Test classes ensure that your code runs as expected and meets Salesforce’s required minimum code coverage of 75% for production deployment.
9. What is a batch Apex?
Batch Apex is used to handle large data sets that exceed the processing limits of standard Apex code. It allows developers to break down large jobs into smaller, manageable chunks for processing.
Explanation:
Batch Apex is particularly useful for handling bulk data operations where processing more than 50,000 records is required.
10. How do you handle exceptions in Apex?
In Apex, exceptions are handled using try, catch, and finally blocks. Developers can catch specific types of exceptions to provide custom error handling or simply catch all exceptions.
Explanation:
Exception handling allows developers to manage unexpected errors gracefully and ensure the stability of the application.
11. What are custom exceptions in Apex?
Custom exceptions in Apex are user-defined exceptions that extend the base Exception class. Developers use custom exceptions to handle specific error conditions that are unique to their application.
Explanation:
Custom exceptions allow developers to implement error-handling logic tailored to their business requirements and make debugging easier.
12. What are static variables in Apex?
Static variables in Apex are variables that retain their value across multiple instances of a class. They are shared across all instances of a class and are initialized once when the class is loaded.
Explanation:
Static variables are useful when data needs to be shared across multiple instances of a class or when maintaining state between different methods.
13. What is a wrapper class in Apex?
A wrapper class is a custom class that developers create to group related objects or collections of data. It can be used to wrap standard or custom objects and other complex data types.
Explanation:
Wrapper classes are helpful for simplifying data management and grouping multiple data types for easier processing in logic and presentation layers.
14. How does Apex handle transactions?
In Apex, all database operations are executed in the context of a transaction. Transactions ensure that all operations either succeed or fail as a unit. Developers can manage transactions using savepoints, commit, and rollback.
Explanation:
Transactions help maintain data integrity by ensuring that partial operations are not committed in case of failure.
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15. What is the purpose of the @InvocableMethod annotation in Apex?
The @InvocableMethod annotation marks a method as callable from a Salesforce flow or process. These methods allow business users to call Apex logic from declarative tools like Flow Builder.
Explanation:
Invocable methods bridge the gap between declarative automation tools and custom Apex logic, offering flexibility in business processes.
16. What is the @AuraEnabled annotation?
The @AuraEnabled annotation is used to expose Apex methods to Lightning components and make them callable from Lightning components’ JavaScript controllers. It is critical in Lightning framework development.
Explanation:
This annotation allows developers to build dynamic, responsive Lightning apps that interact with server-side Apex logic.
17. What is the difference between Database.insert() and insert in Apex?
The insert DML operation automatically rolls back the entire transaction if any error occurs, whereas Database.insert() allows partial success with error handling. The Database.insert() method returns a Database.SaveResult that contains success and failure results.
Explanation:
Using Database.insert() provides greater control by allowing developers to handle errors without rolling back the entire transaction.
18. How do you implement pagination in Apex?
Pagination in Apex can be implemented using SOQL queries with LIMIT and OFFSET clauses. It is often used to retrieve a subset of records to display on a page while navigating through the rest of the data.
Explanation:
Pagination is crucial for improving the performance and user experience of Salesforce pages displaying large amounts of data.
19. What are Apex governor limits for CPU time?
Salesforce imposes CPU time limits to prevent code from consuming excessive server resources. The limit for synchronous Apex is 10,000 milliseconds (10 seconds) and for asynchronous Apex is 60,000 milliseconds (60 seconds).
Explanation:
Exceeding CPU time limits results in an unhandled governor limit exception, terminating the execution of the Apex code.
20. What is the difference between synchronous and asynchronous Apex?
Synchronous Apex executes code immediately, while asynchronous Apex allows for deferred execution, enabling long-running operations to run in the background. Examples of asynchronous Apex include batch Apex, future methods, and queueable Apex.
Explanation:
Asynchronous Apex helps improve performance by running time-consuming operations without blocking the main execution thread.
21. How do you use Queueable Apex?
Queueable Apex is used for asynchronous processing similar to future methods but with more control over job chaining and passing complex objects. It implements the Queueable interface, allowing developers to track jobs and handle results.
Explanation:
Queueable Apex offers greater flexibility than future methods, especially when chaining jobs and managing large objects.
22. What is dynamic SOQL?
Dynamic SOQL allows developers to build a query at runtime as a string, making the query adaptable to different inputs. This is in contrast to static SOQL, which is defined at compile-time.
Explanation:
Dynamic SOQL is useful when you need to query different fields or objects based on user input or other runtime conditions.
23. How does Apex handle recursive triggers?
Apex handles recursive triggers by managing recursion control using static variables or by implementing custom logic to prevent multiple trigger executions on the same record.
Explanation:
Recursive triggers can cause performance issues and governor limit exceptions, so controlling recursion is essential in trigger design.
24
. What is a selector class in Apex?
A selector class is a design pattern used to centralize SOQL queries and data access logic. It separates querying logic from business logic, making code more maintainable and reducing redundancy.
Explanation:
Selector classes follow the separation of concerns principle and help organize complex codebases by isolating data access layers.
25. What are test classes, and why are they important in Apex?
Test classes are Apex classes designed to validate the functionality of other Apex code. They are essential for achieving code coverage, ensuring code quality, and meeting Salesforce’s deployment requirements.
Explanation:
Test classes are mandatory in Salesforce, with a minimum of 75% code coverage required for deploying code to production.
26. How do you test future methods in Apex?
Future methods can be tested using the Test.startTest() and Test.stopTest() methods. These methods encapsulate the execution of asynchronous methods in a synchronous context, allowing for testing.
Explanation:
Without proper testing methods like Test.startTest(), future methods cannot be properly validated during test execution.
27. What are Map, List, and Set in Apex?
Map, List, and Set are data structures in Apex. Map stores key-value pairs, List stores ordered collections of elements, and Set stores unique, unordered elements.
Explanation:
These data structures are essential for handling collections of data efficiently, each serving different use cases in Apex logic.
28. How do you make an Apex class global?
To make an Apex class global, you use the global access modifier. A global class is visible to all namespaces in the Salesforce organization and can be accessed across managed packages.
Explanation:
Global classes are used in managed packages or apps that require broad visibility across multiple namespaces or organizations.
29. What is the purpose of the this keyword in Apex?
The this keyword in Apex refers to the current instance of a class. It is used to distinguish between class fields and method parameters when they have the same name.
Explanation:
The this keyword helps avoid ambiguity in class methods when class properties and method parameters share similar names.
30. What is the System.runAs() method used for?
The System.runAs() method is used in test classes to simulate user contexts and test functionality as if it were being executed by a different user with specific profiles and permissions.
Explanation:
This method helps validate Apex logic under different user permissions and profiles, ensuring code works as expected for various users.
31. What are DML operations in Apex?
DML operations in Apex allow developers to manipulate Salesforce data. Common DML operations include insert, update, delete, undelete, and upsert to create, modify, or delete records.
Explanation:
DML operations are the backbone of data management in Apex, allowing developers to interact with Salesforce objects programmatically.
32. How do you perform callouts in Apex?
Callouts in Apex are used to send HTTP requests or integrate with external systems. Callouts can be done using HttpRequest and HttpResponse classes, and they require @future or Queueable for asynchronous execution.
Explanation:
Apex callouts are essential for integrating Salesforce with external web services and systems for real-time data exchange.
33. What are Custom Metadata types in Apex?
Custom metadata types allow developers to define metadata objects that can be used in Apex code without querying data from the database. This enables faster execution and better scalability.
Explanation:
Custom metadata types are useful for storing configuration or static data that can be referenced across the application without consuming governor limits.
34. What is a Trigger.new in Apex?
Trigger.new is a context variable in Apex triggers that contains the list of new records being inserted or updated in a trigger context. It is available in before and after triggers.
Explanation:
This variable allows developers to access and modify the records that are being processed in the current trigger context.
35. What is the difference between before and after triggers?
Before triggers are used to modify records before they are saved to the database, while after triggers are used to perform actions once the records are committed to the database.
Explanation:
Choosing between before and after triggers depends on whether you need to modify data before saving or perform actions based on saved data.
36. What is a Rollback in Apex?
A rollback in Apex is a way to undo all database operations that have occurred in the current transaction. It is achieved using the Database.rollback() method, which reverts the database to a previously saved state.
Explanation:
The rollback feature is essential for maintaining data integrity in case of errors during the execution of a transaction.
Conclusion
Apex is a robust programming language that empowers developers to extend Salesforce functionality through customized business logic, integrations, and process automation. Mastering the fundamentals and advanced concepts of Apex is crucial for any developer looking to excel in Salesforce-related roles. By studying these top 36 Apex interview questions, you will be better prepared to showcase your skills and knowledge during your next interview, boosting your chances of landing the job.
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