Map Methods

The map methods are all instance methods, that is, they operate on a particular instance of a map. The following are the instance methods for maps.

Note

In the table below, Key_type and Value_type represent the data type of the map key and value respectively, which can be any data type—primitive types, collections, sObjects, user-defined types, and built-in Apex types.
Uniqueness of map keys of user-defined types is determined by the equals and hashCode methods, which you provide in your classes. Uniqueness of keys of all other non-primitive types, such as sObject keys, is determined by comparing the objects’ field values.
Map keys of type String are case-sensitive. Two keys that differ only by the case are considered unique and have corresponding distinct Map entries. Subsequently, the Map methods, including put, get, containsKey, and remove treat these keys as distinct.

Name	Arguments	Return Type	Description
`clear`		Void	Removes all of the key-value mappings from the map.
`clone`		Map (of same type)	Makes a duplicate copy of the map. Note that if this is a map with sObject record values, the duplicate map will only be a shallow copy of the map. That is, the duplicate will have references to each sObject record, but the records themselves are not duplicated. For example: Account a = new Account( Name='Acme', BillingCity='New York'); Map<Integer, Account> map1 = new Map<Integer, Account> {}; map1.put(1, a); Map<Integer, Account> map2 = map1.clone(); map1.get(1).BillingCity = 'San Francisco'; System.assertEquals( map1.get(1).BillingCity, 'San Francisco'); System.assertEquals( map2.get(1).BillingCity, 'San Francisco'); To also copy the sObject records, you must use the `deepClone` method.
`containsKey`	Key type `key`	Boolean	Returns true if the map contains a mapping for the specified `key`. If the key is a string, the key value is case-sensitive. For example: Map<string, string> colorCodes = new Map<String, String>(); colorCodes.put('Red', 'FF0000'); colorCodes.put('Blue', '0000A0'); Boolean contains = colorCodes.containsKey('Blue'); System.assertEquals(contains, True);
`deepClone`		Map (of the same type)	Makes a duplicate copy of a map, including sObject records if this is a map with sObject record values. For example: Account a = new Account( Name='Acme', BillingCity='New York'); Map<Integer, Account> map1 = new Map<Integer, Account> {}; map1.put(1, a); Map<Integer, Account> map2 = map1.deepClone(); map1.get(1).BillingCity = 'San Francisco'; System.assertEquals(map1.get(1). BillingCity, 'San Francisco'); System.assertEquals(map2.get(1). BillingCity, 'New York'); To make a shallow copy of a map without duplicating the sObject records it contains, use the `clone()` method.
`get`	Key type `key`	`Value_type`	Returns the value to which the specified `key` is mapped, or `null` if the map contains no value for this key. If the key is a string, the key value is case-sensitive. For example: Map<String, String> colorCodes = new Map<String, String>(); colorCodes.put('Red', 'FF0000'); colorCodes.put('Blue', '0000A0'); String code = colorCodes.get('Blue'); System.assertEquals(code, '0000A0'); // The following is not a color // in the map String code2 = colorCodes.get('Magenta'); System.assertEquals(code2, null);
`getSObjectType`		Schema.SObjectType	Returns the token of the sObject type that makes up the map values. Use this with describe information, to determine if a map contains sObjects of a particular type. For example: Account a = new Account( Name='Acme'); insert a; // Create a generic sObject // variable s SObject s = Database.query ('SELECT Id FROM Account ' + 'LIMIT 1'); // Verify if that sObject // variable // is an Account token System.assertEquals( s.getSObjectType(), Account.sObjectType); // Create a map of generic // sObjects Map<Integer, Account> M = new Map<Integer, Account>(); // Verify if the list of sObjects // contains Account tokens System.assertEquals( M.getSObjectType(), Account.sObjectType); Note that this method can only be used with maps that have sObject values. For more information, see Understanding Apex Describe Information.
`isEmpty`		Boolean	Returns true if the map has zero key-value pairs. For example: Map<String, String> colorCodes = new Map<String, String>(); Boolean empty = colorCodes.isEmpty(); system.assertEquals(empty, true);
`keySet`		Set of `Key_type`	Returns a set that contains all of the keys in the map. For example: Map<String, String> colorCodes = new Map<String, String>(); colorCodes.put('Red', 'FF0000'); colorCodes.put('Blue', '0000A0'); Set <String> colorSet = new Set<String>(); colorSet = colorCodes.keySet();
`put`	Key `key`, Value `value`	`Value_type`	Associates the specified `value` with the specified `key` in the map. If the map previously contained a mapping for this key, the old value is returned by the method and then replaced. If the key is a string, the key value is case-sensitive. For example: Map<String, String> colorCodes = new Map<String, String>(); colorCodes.put('Red', 'ff0000'); colorCodes.put('Red', '#FF0000'); // Red is now #FF0000
`putAll`	Map `m`	Void	Copies all of the mappings from the specified map `m` to the original map. The new mappings from `m` replace any mappings that the original map had.
`putAll`	sObject[] `l`		If the map is of IDs or Strings to sObjects, adds the list of sObject records `l` to the map in the same way as the Map constructor with this input.
`remove`	Key `key`	`Value_type`	Removes the mapping for this `key` from the map if it is present. The value is returned by the method and then removed. If the key is a string, the key value is case-sensitive. For example: Map<String, String> colorCodes = new Map<String, String>(); colorCodes.put('Red', 'FF0000'); colorCodes.put('Blue', '0000A0'); String myColor = colorCodes.remove('Blue'); String code2 = colorCodes.get('Blue'); System.assertEquals(code2, null);
`size`		Integer	Returns the number of key-value pairs in the map. For example: Map<String, String> colorCodes = new Map<String, String>(); colorCodes.put('Red', 'FF0000'); colorCodes.put('Blue', '0000A0'); Integer mSize = colorCodes.size(); system.assertEquals(mSize, 2);
`values`		list of `Value_type`	Returns a list that contains all of the values in the map in arbitrary order. For example: Map<String, String> colorCodes = new Map<String, String>(); colorCodes.put('Red', 'FF0000'); colorCodes.put('Blue', '0000A0'); List<String> colors = new List<String>(); colors = colorCodes.values();

For more information on maps, see Maps.