Comparator Interface

Implement different sort orders with the Comparator interface’s compare() method, and pass the Comparator as a parameter to List.sort(). Your implementation must explicitly handle null inputs in the compare() method to avoid a null pointer exception.

Namespace

System

Comparator Methods

The following are methods for Comparator.

compare(var1, var2)

Compares the two arguments and returns a negative integer, zero, or a positive integer depending on whether the first argument is less than, equal to, or greater than the second argument.

Signature

public Integer compare(T var1, T var2)

Parameters

var1: Type: T; T - The type determined by the parameterized type of the Comparator. For example, if the class implements Comparator<Account> then var1 and var2 are of type Account .
var2: Type: T; T - The type determined by the parameterized type of the Comparator. For example, if the class implements Comparator<Account> then var1 and var2 are of type Account .

Return Value

Type: Integer

Comparator Example Implementation

Use the Comparator interface to impose different kinds of sorting.

This example implements two different ways of sorting employees.

The following example tests the implementation:

Apex Reference Guide