A set is an unordered collection of primitives that do not contain any duplicate elements. For example, the following table represents a set of city names:
| 'San Francisco' | 'New York' | 'Paris' | 'Tokyo' |
new Set<String>()
The following are ways to declare and populate a set:
Set<String> s1 = new Set<String>{'a', 'b + c'}; // Defines a new set with two elements Set<String> s2 = new Set<String>(s1); // Defines a new set that contains the // elements of the set created in the previous step
To access elements in a set, use the system methods provided by Apex. For example:
Set<Integer> s = new Set<Integer>(); // Define a new set s.add(1); // Add an element to the set System.assert(s.contains(1)); // Assert that the set contains an element s.remove(1); // Remove the element from the set
For more information, including a complete list of all supported set system methods, see Set Methods.