Apex List Class: Enhance Salesforce Development with Key Practices

In Apex, the programming language used for Salesforce development, a List is a collection class designed to store elements in a specific order. Its ability to hold duplicate values and dynamic size characterizes it, meaning elements can be added or removed at runtime. Lists are strongly typed, requiring declaration for a specific data type, such as List<String> or List<Account>. 

This ordered collection differs from other collection types in Apex, like Sets, which store unique elements in an unordered fashion, and Maps, which are collections of key-value pairs where each unique key is associated with a specific value. 

Comparison with Sets and Maps

• Sets:
  • An unordered collection of unique elements.
  • Cannot access elements by index.
  • Useful for ensuring uniqueness and for operations like union and intersection.
• Maps:
  • • A collection of key-value pairs.
    • Each key maps to a single value, and the keys are unique.
    • Useful for fast retrieval and updating of data based on keys.

  

When to Use Lists vs. Sets vs. Maps

Also Read – Salesforce Coding – Best Practices

Common Operations with Lists

Adding Items to a List (add method)

To add an item to a List, you use the add method. This appends the item to the end of the List.

List<String> fruits = new List<String>();

fruits.add(‘Apple’);

fruits.add(‘Banana’);

Accessing Elements in a List (Index Access)

Access elements in a List by their index. List indices start at 0.

String firstFruit = fruits[0]; // Accesses the first element, ‘Apple’

Iterating Over a List (for loops)

You can use a for loop to go through each element in a List.

for(String fruit : fruits) {

    System.debug(fruit);

}

Or, you can use a traditional for loop with an index:

for(Integer i = 0; i < fruits.size(); i++) {

    System.debug(fruits[i]);

}

Removing Items from a List (remove and clear methods)

To remove an item from a List, you can use the remove method in two ways:

• By index:

fruits.remove(1); // Removes the item at index 1 (e.g., ‘Banana’)

• By object:

fruits.remove(‘Apple’); // Removes ‘Apple’ from the List

Best Practices and Tips

Use Proper Data Types

Always specify the data type of the elements in the List. It prevents runtime errors and improves code clarity.

List<String> names = new List<String>(); // Good Practice

List names = new List(); // Avoid this

Initialize Lists Properly

When possible, initialize Lists with inline data for readability and conciseness.

List<String> colors = new List<String>{‘Red’, ‘Green’, ‘Blue’};

Avoid Unnecessary Operations

Prevent Redundant Looping: Minimize looping over Lists unnecessarily. Each iteration adds to CPU time, especially important in Salesforce given its governor limits.

Use Bulk Operations

When dealing with sObjects, always consider bulk operations to avoid hitting governor limits. For example, when adding sObjects to a List for a database operation, add them in bulk rather than one at a time.

Also Read – Apex Best Practices in Salesforce

List Size and Capacity

If you know the number of elements a List will have, consider initializing it with that capacity to optimize memory usage.

List<String> names = new List<String>(capacity);

Check for Nulls and Bounds 

Before accessing List elements, ensure the List is not null and the index is within bounds.

if (myList != null && index < myList.size()) {

    // Safe to access myList[index]

}

Iteration Techniques

• Choose the Right Iteration Method: Use enhanced for loops for simple traversals. Use a traditional for loop for scenarios where you need the index or want to modify the List during iteration.
• Use Collections Methods Wisely: Be aware of the List methods like sort(). Implement custom sorting logic if needed. Write efficient custom logic for reversing as Apex doesn’t have a built-in method.
• Simplicity: Write clear and simple logic while manipulating Lists. Complex list operations can be split into multiple steps for clarity.

Summing Up

Mastering Apex Lists in Salesforce is a crucial step for any aspiring or seasoned developer looking to enhance their coding efficiency and versatility within the platform. Understanding how Lists differ from other collection types like Sets and Maps, and implementing best practices, will significantly elevate the quality and performance of your Salesforce applications.

But learning doesn’t stop at understanding concepts; it’s about putting them into practice. That’s where saasguru steps in to bridge the gap between knowledge and real-world application. Join our thriving saasguru community on Slack, a space where Salesforce enthusiasts and experts converge to share insights, challenges, and solutions.  

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