Salesforce Developer – Apex Basics Questions

Apex Basics - Q&A

1. Q1. What are the key characteristics of Apex as a programming language?
   Ans:
   - Strongly-typed: Requires explicit variable declaration
   - Object-oriented: Supports classes, interfaces, inheritance
   - Governor limits: Runtime restrictions (e.g., 100 SOQL queries/transaction)
   - On-demand: Executes when invoked (triggers, controllers, etc.)
2. Q2. Explain the Apex execution context and governor limits.
   Ans: Apex runs in a multi-tenant environment with strict limits:
   - CPU timeout: 10,000ms synchronous, 60,000ms async
   - Heap size: 6MB synchronous, 12MB async
   - SOQL queries: 100 synchronous/transaction
   Pro Tip: Always bulkify code to avoid limits.
3. Q3. How do you implement a basic Apex class with proper syntax?
   Ans: Example:
   

   public class AccountProcessor {
     // Class variable
     private static Integer count = 0;
     
     // Method with parameters
     public static void updateAccountStatus(List accounts) {
       for(Account acc : accounts) {
         acc.Status__c = 'Active';
       }
       update accounts; // DML operation
     }
   }

4. Q4. What are the different ways to invoke Apex code?
   Ans:
   - Triggers: On record events (insert/update)
   - Visualforce controllers: Page interactions
   - Lightning Web Components: @AuraEnabled methods
   - Scheduled/Batch: Asynchronous execution
   - Anonymous Apex: Developer Console execution
5. Q5. How do you handle exceptions in Apex?
   Ans: Using try-catch blocks:
   

   try {
     Account acc = [SELECT Id FROM Account WHERE Name = 'Nonexistent'];
   } catch(QueryException qe) {
     System.debug('Error: ' + qe.getMessage());
   } finally {
     // Cleanup code
   }

6. Q6. What are static variables in Apex and when would you use them?
   Ans: Static variables:
   - Maintain state across transaction boundaries
   - Shared across all class instances
   - Common uses:
   * Counters in triggers
   * Flags to prevent recursive triggers
   * Caching frequently used data
7. Q7. How do you write a unit test for a simple Apex class?
   Ans: Example test class:
   

   @isTest
   private class AccountProcessorTest {
     @isTest static void testUpdateAccountStatus() {
       // Setup test data
       Account testAcc = new Account(Name='Test');
       insert testAcc;
       
       // Execute method
       Test.startTest();
       AccountProcessor.updateAccountStatus(new List{testAcc});
       Test.stopTest();
       
       // Verify results
       Account updatedAcc = [SELECT Status__c FROM Account WHERE Id = :testAcc.Id];
       System.assertEquals('Active', updatedAcc.Status__c);
     }
   }

8. Q8. What are the different types of collections in Apex?
   Ans:
   - Lists: Ordered, allows duplicates (most common)
   - Sets: Unordered, unique elements (good for deduplication)
   - Maps: Key-value pairs (fast lookup by key)
   Example: Map accountMap = new Map([SELECT Id FROM Account]);
9. Q9. How do you prevent recursive trigger execution?
   Ans: Common patterns:
   1. Static variable flag:
   

   public class TriggerHelper {
     public static Boolean isFirstRun = true;
   }

   2. Handler pattern: Centralized trigger logic with execution control
10. Q10. What are the different DML operations in Apex?
    Ans:
    - insert, update, upsert, delete, undelete, merge
    - Database methods (better for error handling):
    Database.insert(records, allOrNone)
    - Best practice: Always use bulk DML operations
11. Q11. How do you implement custom exceptions in Apex?
    Ans: Create custom exception classes:
    

    public class MyCustomException extends Exception {}
                  
    // Usage:
    if(someCondition) {
      throw new MyCustomException('Error message');
    }

12. Q12. What are transaction control methods in Apex?
    Ans:
    - Savepoint: Create rollback points
    Savepoint sp = Database.setSavepoint();
    - Rollback: Revert to savepoint
    Database.rollback(sp);
13. Q13. How do you debug Apex code effectively?
    Ans:
    - System.debug() statements (view in Developer Console)
    - Debug logs with appropriate log levels
    - Checkpoints in Salesforce DX
    - Anonymous Apex for quick testing
14. Q14. What are the best practices for writing bulk-safe Apex?
    Ans:
    - Process records in collections (not single-record)
    - Move queries/DML outside loops
    - Use maps for efficient lookups
    - Implement error handling for partial successes
15. Q15. How do you compare Apex with other programming languages?
    Ans:
    - Similar to Java: Syntax, OOP concepts
    - Unique aspects:
    * Governor limits
    * Tight integration with Salesforce data model
    * No file system access
    * Automatic transaction management