Understanding Integers in Apex | Variables and Data Types

Integers are one of the fundamental primitive data types in Apex. They represent whole numbers without decimal points and are used for counting, indexing, and mathematical calculations.

Integer Declaration

In Apex, you can declare integer variables using the Integer keyword:

Integer myNumber = 42;
Integer count = 0;
Integer negativeValue = -10;

Unlike some other programming languages, you don't need to specify different integer types based on size - the Integer type in Apex handles a wide range of values.

Integer Range

The Integer data type in Apex can store values from -2,147,483,648 to 2,147,483,647 (32-bit signed integer). If you need to work with larger numbers, you can use the Long data type instead.

// This is the maximum value an Integer can hold
Integer maxValue = 2147483647;

// This is the minimum value an Integer can hold
Integer minValue = -2147483648;

Basic Operations

You can perform various arithmetic operations with integers:

Integer a = 10;
Integer b = 3;

// Addition
Integer sum = a + b;        // 13

// Subtraction
Integer difference = a - b; // 7

// Multiplication
Integer product = a * b;    // 30

// Division
Integer quotient = a / b;   // 3 (note: integer division truncates decimal values)

// Modulus (remainder)
Integer remainder = a % b;  // 1

Type Conversion

Sometimes you'll need to convert between integers and other data types:

// String to Integer
String numText = '25';
Integer convertedNum = Integer.valueOf(numText);

// Decimal to Integer (truncates decimal portion)
Decimal price = 29.95;
Integer approxPrice = price.intValue();  // 29

// Long to Integer
Long largeNumber = 1000L;
Integer normalNumber = largeNumber.intValue();

Common Methods

The Integer class in Apex provides several useful methods:

// valueOf() converts other types to Integer
Integer num1 = Integer.valueOf('42');
Integer num2 = Integer.valueOf(42.5);  // Truncates to 42

// abs() returns the absolute value
Integer negative = -25;
Integer positive = Math.abs(negative);  // 25

// max() and min() find the larger or smaller of two numbers
Integer larger = Math.max(10, 20);    // 20
Integer smaller = Math.min(10, 20);   // 10

Using Integers in Collections

Integers are commonly used in collections like Lists and Maps:

// List of integers
List<Integer> numberList = new List<Integer>{1, 2, 3, 4, 5};

// Adding to the list
numberList.add(6);

// Accessing elements (indexing starts at 0)
Integer thirdNumber = numberList[2];  // 3

// Map with Integer keys
Map<Integer, String> employeeIds = new Map<Integer, String>();
employeeIds.put(1001, 'John Doe');
employeeIds.put(1002, 'Jane Smith');

Best Practices

Use descriptive variable names that indicate what the integer represents (e.g., customerId instead of just id).
Check for boundary conditions when working with integers to avoid overflow errors.
Be aware of integer division - dividing two integers always returns an integer, dropping any decimal portion.
Use Integer.valueOf() carefully - it will throw an exception if the string cannot be converted to an integer.