Apex Data Types

Apex supports various data types categorized into primitive types, collections, sObjects, and complex types.

Below is a comprehensive list with examples.

1. Primitive Data Types

These store single values such as numbers, text, and dates.

Data Type	Description	Example
String	Sequence of characters	String greeting = 'Hello, Salesforce!';
Boolean	Stores true or false	Boolean isActive = true;
Integer	Whole numbers	Integer rollNumber = 1001;
Long	Large whole numbers	Long worldPopulation = 8000000000L;
Double	Floating-point numbers	Double pi = 3.14159;
Decimal	High-precision floating-point numbers	Decimal price = 99.99;
ID	Salesforce record ID	Id recordId = '0015g00000ABCD';
Date	Stores date without time	Date today = Date.today();
Time	Stores time only	Time now = Time.newInstance(14, 30, 0, 0);
Datetime	Stores both date and time	Datetime now = Datetime.now();

DeveloperConsole: anonymous window(Primitive Data Types)

       
        String greeting = 'Hello, Salesforce!';
        Boolean isActive = true;
        Integer rollNumber = 1001;
        Long worldPopulation = 8000000000L;
        Double pi = 3.14159;
        Decimal price = 99.99;
        Id recordId = '0015g00000ABCD';
        Date today = Date.today();
        Time now = Time.newInstance(14, 30, 0, 0);
        Datetime now = Datetime.now();
        
        System.debug(greeting);
        System.debug(isActive);
        System.debug(rollNumber);
        System.debug(worldPopulation);
        System.debug(pi);
        System.debug(price);
        System.debug(recordId);
        System.debug(today);
        System.debug(now);
        System.debug(now);
        
                

2. Collection Data Types

Collections store multiple values in different formats.

Collection Type	Description	Example
List	Ordered collection of elements	List<String> names = new List<String>{'Alice', 'Bob'};
Set	Unordered collection of unique elements	Set<Integer> uniqueNumbers = new Set<Integer>{1, 2, 3};
Map	Key-value pairs	Map<String, Integer> scoreMap = new Map<String, Integer>{'Alice' => 90, 'Bob' => 85};

DeveloperConsole: anonymous window(Lists, Sets, Maps)

        
        // List Example
List names = new List{'Alice', 'Bob', 'Charlie'};
System.debug(names[0]); // Output: Alice

// Set Example
Set uniqueNumbers = new Set{10, 20, 30};
System.debug(uniqueNumbers.contains(20)); // Output: true

// Map Example
Map ageMap = new Map{'Alice' => 25, 'Bob' => 30};
System.debug(ageMap.get('Alice')); // Output: 25
        

3. sObject Data Types

Used for storing Salesforce object records.

sObject Type	Description	Example
Standard Object	Salesforce standard object	Account acc = new Account(Name='ABC Corp');
Custom Object	User-defined object	MyCustomObject__c obj = new MyCustomObject__c(Name='Test');

DeveloperConsole: anonymous window(sObject)

       
        // Standard Object
Account acc = new Account(Name = 'Tech Corp', Industry = 'IT');
insert acc;
System.debug(acc.Id);

// Custom Object
MyCustomObject__c customObj = new MyCustomObject__c(Name = 'Custom Record');
insert customObj;
System.debug(customObj.Id);
        

4. Enum Data Type

An enumdefines a fixed set of constants.

DeveloperConsole: anonymous window(Enum)

        public enum Status { NEW, IN_PROGRESS, COMPLETED }
        Status currentStatus = Status.NEW;
        System.debug(currentStatus); // Output: NEW
       
        

5. Complex & Special Data Types

Data Type	Description	Example
Blob	Stores binary data	Blob imageData = Blob.valueOf('sample data');
Object	Generic type	Object data = 'Hello';

DeveloperConsole: anonymous window(Blob and Object)

           
       
            // Blob Example
            Blob imageData = Blob.valueOf('sample data');
            System.debug(imageData);

            // Object Example
            Object data = 'Dynamic Type';
            System.debug(data);
       
        

6. Null Values in Apex

- Any uninitialized variable in Apex defaults to `null`.

DeveloperConsole: anonymous window

        String str;
        System.debug(str); // Output: null
    
        Integer number;
        System.debug(number); // Output: null
    
        Boolean flag;
        System.debug(flag); // Output: false
        

Summary of Apex Data Types

Category	Data Types
Primitive	String, Boolean, Integer, Long, Double, Decimal, ID, Date, Time, Datetime
Collection	List, Set, Map
sObject	Standard Object, Custom Object
Enum	User-defined constants
Complex & Special	Blob, Object