Sets

This table represents a set of strings that uses city names:

Sets can contain collections that can be nested within one another. For example, you can have a set of lists of sets of Integers. A set can contain up to seven levels of nested collections inside it, that is, up to eight levels overall.

1Set<String> myStringSet = new Set<String>();

The following example shows how to create a set with two hardcoded string values.

1// Defines a new set with two elements
2Set<String> set1 = new Set<String>{'New York', 'Paris'};

To access elements in a set, use the system methods provided by Apex. For example:

1// Define a new set
2Set<Integer> mySet = new Set<Integer>();
3// Add two elements to the set
4mySet.add(1);
5mySet.add(3);
6// Assert that the set contains the integer value we added
7System.assert(mySet.contains(1)); 
8// Remove the integer value from the set
9mySet.remove(1);

The following example shows how to create a set from elements of another set.

1// Define a new set that contains the
2// elements of the set created in the previous example
3Set<Integer> mySet2 = new Set<Integer>(mySet);
4// Assert that the set size equals 1
5// Note: The set from the previous example contains only one value
6System.assert(mySet2.size() == 1);

For more information, including a complete list of all supported set system methods, see Set Class.