In Apex, the Map class provides a collection of key-value pairs, where each key is unique. It offers several methods to manipulate and retrieve data from the map. Map methods in Apex provide a wide range of functionality, including searching for values, checking for key existence, and merging maps together. Let’s explore some of the commonly used methods with examples:
Map Methods in Apex
The following are methods for Map.
clear()
clear() method is used to remove all key-value pairs from a Map object, making it empty.
// Creating a map to store student names and their corresponding scores
Map<String, Integer> studentScores = new Map<String, Integer>();
studentScores.put('John', 85);
studentScores.put('Emily', 92);
studentScores.put('Michael', 78);
// Printing the original map
System.debug('Original Map: ' + studentScores);
// Clearing the map using clear() method
studentScores.clear();
// Printing the cleared map
System.debug('Cleared Map: ' + studentScores);
clone()
In Apex, the clone() method is used to create a shallow copy of a Map object.
Creating a map to store employee details
Map<String, String> employeeDetails = new Map<String, String>();
employeeDetails.put('John', 'Manager');
employeeDetails.put('Emily', 'Developer');
employeeDetails.put('Michael', 'Analyst');
// Creating a shallow copy of the map using clone() method
Map<String, String> clonedMap = employeeDetails.clone();
// Modifying the cloned map
clonedMap.put('Emily', 'Senior Developer');
clonedMap.put('Michael', 'Senior Analyst');
// Printing the original map
System.debug('Original Map: ' + employeeDetails);
// Printing the cloned map
System.debug('Cloned Map: ' + clonedMap);
containsKey(key)
Checks if the map contains a specific key and returns a boolean value. Example:
Map<String, Integer> studentScores = new Map<String, Integer>();
studentScores.put('John', 85);
studentScores.put('Emily', 92);
studentScores.put('Michael', 78);
Boolean containsJohn = studentScores.containsKey('John');
System.debug('Does Map contains John '+containsJohn);
deepClone()
In Apex, the deepClone() method is used to create a deep copy of a Map object, including both keys and values.
equals(map2)
In Apex, the equals(map2) method is used to compare two Map objects for equality. It returns a boolean value indicating whether the two maps have the same key-value pairs
// Creating two maps to compare
Map<String, Integer> map1 = new Map<String, Integer>();
map1.put('John', 85);
map1.put('Emily', 92);
map1.put('Michael', 78);
Map<String, Integer> map2 = new Map<String, Integer>();
map2.put('John', 85);
map2.put('Emily', 92);
map2.put('Michael', 78);
Map<String, Integer> map3 = new Map<String, Integer>();
map3.put('John', 85);
map3.put('Emily', 92);
map3.put('Michael', 80);
// Comparing map1 with map2 using equals() method
Boolean isEqual1 = map1.equals(map2);
System.debug('Are map1 and map2 equal? ' + isEqual1); // Outputs: true
// Comparing map1 with map3 using equals() method
Boolean isEqual2 = map1.equals(map3);
System.debug('Are map1 and map3 equal? ' + isEqual2); // Outputs: false
get(key)
Retrieves the value associated with the specified key. If the key is not found, it returns null.
Map<String, Integer> studentScores = new Map<String, Integer>();
studentScores.put('John', 85);
studentScores.put('Emily', 92);
studentScores.put('Michael', 78);
Integer johnScore = studentScores.get('John');
System.debug('JohnScore '+johnScore);
getSObjectType()
Returns the token of the sObject type that makes up the map values.
hashCode()
Returns the hashcode corresponding to this map.
isEmpty()
Checks if the map is empty and returns a boolean value. Example:
Map<String, Integer> studentScores = new Map<String, Integer>();
Boolean isMapEmpty = studentScores.isEmpty();
System.debug('before adding elements to map. isMapEmpty '+isMapEmpty); //returns true
studentScores.put('John', 85);
studentScores.put('Emily', 92);
studentScores.put('Michael', 78);
isMapEmpty = studentScores.isEmpty();
System.debug('After adding elements. isMapEmpty '+isMapEmpty); // returns false
keySet()
In Apex, the keySet() method of the Map class returns a Set containing all the keys present in the map. This allows you to access and iterate through the keys separately from the values.
// Creating a map to store student names and their corresponding scores
Map<String, Integer> studentScores = new Map<String, Integer>();
studentScores.put('John', 85);
studentScores.put('Emily', 92);
studentScores.put('Michael', 78);
// Retrieving the set of keys using keySet() method
Set<String> keys = studentScores.keySet();
// Iterating through the set of keys and printing each key and its associated score
for (String key : keys) {
Integer score = studentScores.get(key);
System.debug('Student: ' + key + ', Score: ' + score);
}
put(key, value)
This method adds a key-value pair to the map or updates the value if the key already exists. Example:
Map<String, Integer> studentScores = new Map<String, Integer>();
studentScores.put('John', 85);
studentScores.put('Emily', 92);
studentScores.put('Michael', 78);
putAll(fromMap)
In Apex, the putAll(fromMap) method is used to add all key-value pairs from one Map object to another. It allows you to merge the contents of one map into another map.
// Create two maps to demonstrate putAll() method
Map<String, Integer> map1 = new Map<String, Integer>();
map1.put('A', 1);
map1.put('B', 2);
Map<String, Integer> map2 = new Map<String, Integer>();
map2.put('C', 3);
map2.put('D', 4);
// Add all key-value pairs from map1 to map2 using putAll() method
map2.putAll(map1);
// Print the contents of map2
System.debug('Map2: ' + map2);
putAll(sobjectArray)
Adds the list of sObject records to a map declared as Map<ID, sObject> or Map<String, sObject>
remove(key)
Removes the key-value pair associated with the specified key from the map. Example:
Map<String, Integer> studentScores = new Map<String, Integer>();
studentScores.put('John', 85);
studentScores.put('Emily', 92);
studentScores.put('Michael', 78);
System.debug('Before Removal '+studentScores);
studentScores.remove('Michael');
System.debug('After removal '+studentScores);
size()
returns the number of key-value pairs in the map. Example:
Map<String, Integer> studentScores = new Map<String, Integer>();
studentScores.put('John', 85);
studentScores.put('Emily', 92);
studentScores.put('Michael', 78);
Integer mapSize = studentScores.size();
System.debug('mapSize '+mapSize);
toString()
In Apex, the toString() method is used to convert a Map object into a String representation.
// Create a Map object
Map<String, Integer> mapt = new Map<String, Integer>();
mapt.put('A', 1);
mapt.put('B', 2);
mapt.put('C', 3);
// Convert the Map to a String using toString() method
String mapString = mapt.toString();
// Print the String representation of the Map
System.debug('Map String: ' + mapString);
values()
Returns a list of all the values in the map. Example:
Map<String, Integer> studentScores = new Map<String, Integer>();
studentScores.put('John', 85);
studentScores.put('Emily', 92);
studentScores.put('Michael', 78);
List<Integer> scores = studentScores.values();
System.debug('scores '+scores);
- Map methods in Apex provide powerful functionality for working with key-value pairs in Salesforce development.
- Developers can leverage various map methods to manipulate and analyze data stored in maps efficiently.
- Understanding the available map methods is essential for effectively managing and manipulating data structures in Apex.
- By utilizing map methods in Apex, developers can perform operations such as adding, removing, and iterating over key-value pairs in a map.
- Efficient utilization of map methods in Apex can enhance the performance and readability of code when dealing with collections of data.
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