Salesforce Apex Interview Questions and Answers

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Salesforce Apex is a robust, strongly-typed, object-oriented programming language that plays a crucial role in Salesforce development. Whether you’re preparing for an interview or looking to brush up on your skills, understanding key concepts and functionalities of Apex is essential. This guide provides a comprehensive list of the top Salesforce Apex interview questions, along with detailed answers, to help you prepare effectively.

These questions cover a range of topics, from the basics of Apex and its usage in Salesforce to advanced topics such as exception handling, batch processing, and custom controllers. By familiarizing yourself with these questions and answers, you’ll be better equipped to demonstrate your knowledge and skills in Salesforce development during your next interview.

Table of Contents

1. What is Apex in Salesforce?

Apex is a strongly-typed, object-oriented programming language that allows developers to execute flow and transaction control statements on Salesforce servers in conjunction with calls to the API. It uses syntax that looks like Java and acts like database stored procedures. Apex enables developers to add business logic to most system events, including button clicks, related record updates, and Visualforce pages.

2. What are Governor Limits in Salesforce Apex?

Governor Limits are runtime limits enforced by Salesforce to ensure the efficient use of shared resources and to prevent any single tenant from monopolizing the resources. These limits include restrictions on the number of DML operations, the number of SOQL queries, the number of records retrieved, and CPU usage time. For example, a single transaction can retrieve a maximum of 50,000 records, and a maximum of 100 SOQL queries can be executed in a single transaction.

3. Explain the differences between SOQL and SOSL.

SOQL (Salesforce Object Query Language): Used to retrieve records from Salesforce objects, SOQL is similar to SQL and can retrieve data from a single object or multiple related objects. It supports WHERE and ORDER BY clauses.
SOSL (Salesforce Object Search Language): Used to perform text searches against multiple objects and fields. SOSL is useful for searching across multiple objects and fields within those objects in a single query. It returns records that match the search terms, with each search result containing the record ID and the fields that matched the search terms.

4. How do you handle exceptions in Apex?

Apex provides a way to handle exceptions using try-catch-finally blocks. When an error occurs in the try block, control is transferred to the catch block. The finally block, if present, executes regardless of whether an exception was thrown. Here is an example:

sfs

5. What are the different types of collections in Apex?

Apex provides three types of collections:

Lists: Ordered collections of elements that are accessible by their indices. Lists can contain elements of any data type, including primitives, sObjects, user-defined types, Apex objects, or other collections.

List<String> myList = new List<String>{'Apple', 'Banana', 'Cherry'};

Sets: Unordered collections of unique elements. Sets are useful for ensuring that there are no duplicate values.

Set<Integer> mySet = new Set<Integer>{1, 2, 3, 4, 5};

Maps: Collections of key-value pairs, where each unique key maps to a single value. Maps can be used to store data in a way that makes it easy to retrieve a value based on its key.

Map<String, Integer> myMap = new Map<String, Integer>{'Apple' => 1, 'Banana' => 2, 'Cherry' => 3};

6. Describe the process of creating a custom controller in Apex.

A custom controller is an Apex class that implements all the logic for a page without leveraging a standard controller. To create a custom controller, follow these steps:

Create an Apex Class: Write an Apex class with methods to handle the business logic. This class will act as the custom controller.

public class MyCustomController {
    public String accountName { get; set; }

    public MyCustomController() {
        accountName = '';
    }

    public void saveAccount() {
        Account acc = new Account(Name = accountName);
        insert acc;
    }
}

Use the Custom Controller in a Visualforce Page: Reference the custom controller in a Visualforce page and bind it to the page components.

<apex:page controller="MyCustomController">
    <apex:form>
        <apex:inputText value="{!accountName}" label="Account Name"/>
        <apex:commandButton action="{!saveAccount}" value="Save"/>
    </apex:form>
</apex:page>

In this example, the MyCustomController class handles the logic for creating a new account.

7. What is the use of the `@future` annotation in Apex?

The @future annotation is used to mark methods that should run asynchronously. Methods with this annotation are queued for execution when Salesforce has resources available. This is useful for long-running operations or when the current execution context doesn’t allow certain operations, such as making callouts to external web services.

Key points about @future methods:

Must be static and return void.
Can only take primitive data types or collections of primitive data types as parameters.
Cannot call another @future method.
Often used to avoid governor limits, such as DML limits or callout limits.

Example of a @future method:

public class FutureExample {
    @future
    public static void futureMethod(Set<Id> recordIds) {
        // Long-running operations or callouts
        List<Account> accounts = [SELECT Id, Name FROM Account WHERE Id IN :recordIds];
        // Perform some processing
    }
}

8. How do you implement batch processing in Apex?

Batch processing in Apex allows you to process large volumes of data in chunks. To implement batch processing, create a class that implements the Database.Batchable interface. This interface requires three methods: start, execute, and finish.

Example:

global class BatchExample implements Database.Batchable<SObject> {
    global Database.QueryLocator start(Database.BatchableContext BC) {
        return Database.getQueryLocator('SELECT Id, Name FROM Account');
    }

    global void execute(Database.BatchableContext BC, List<SObject> scope) {
        List<Account> accountsToUpdate = new List<Account>();
        for (Account acc : (List<Account>)scope) {
            acc.Name = acc.Name + ' - Updated';
            accountsToUpdate.add(acc);
        }
        update accountsToUpdate;
    }

    global void finish(Database.BatchableContext BC) {
        System.debug('Batch processing finished.');
    }
}

To run the batch job:

BatchExample batch = new BatchExample();
Database.executeBatch(batch);

9. Explain the purpose of the `Database.SaveResult` class.

The Database.SaveResult class is used to capture the results of DML operations (insert, update, delete) performed using the Database class methods. It provides information about the success or failure of each record operation and includes methods to retrieve error messages.

Example usage:

List<Account> accounts = new List<Account>{
    new Account(Name='Account1'),
    new Account(Name='Account2')
};

Database.SaveResult[] results = Database.insert(accounts, false);

for (Database.SaveResult result : results) {
    if (result.isSuccess()) {
        System.debug('Successfully inserted record with ID: ' + result.getId());
    } else {
        for (Database.Error error : result.getErrors()) {
            System.debug('Error: ' + error.getMessage());
        }
    }
}

In this example, Database.insert is used with the allOrNone parameter set to false, which allows partial success. The SaveResult objects provide detailed information about the outcome.

10. How do you test Apex code and what are test classes in Salesforce?

Testing Apex code is crucial to ensure code quality and to meet Salesforce’s requirement that at least 75% of the code is covered by tests before deployment. Test classes in Salesforce are used to write and run unit tests. These classes use the @isTest annotation and contain test methods to validate the functionality of Apex code.

Key components of a test class:

Test Method: A method annotated with @isTest to indicate it is a test method.
Test Data: Create test data within the test class to avoid dependency on existing data.
System.assert: Use assertions to verify that the code behaves as expected.

Example of a test class:

@isTest
public class MyApexClassTest {
    @isTest
    static void testMyMethod() {
        // Create test data
        Account testAccount = new Account(Name='Test Account');
        insert testAccount;

        // Call the method to be tested
        MyApexClass.myMethod(testAccount.Id);

        // Verify results using assertions
        Account resultAccount = [SELECT Name FROM Account WHERE Id = :testAccount.Id];
        System.assertEquals('Test Account - Updated', resultAccount.Name);
    }
}

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