Code used in map basic methods tutorial on SFDC Stop (https://youtu.be/MKqylTF4yGo)

mapbasicmethods.cls

Map Data Structure in Apex
-------------------------------

Def: A map is a collection of key-value pairs where each unique key maps to a single value.

1. Creating a Map of Employees
-------------------------------

Map<Integer, String> employeesMap = new Map<Integer, String>();
System.debug(employeesMap);

Map<Integer, String> employeesMap = new Map<Integer, String>{
    1 => 'Richard',
    2 => 'Monica',
    3 => 'Erlich',
    4 => 'Dinesh'
};
System.debug(employeesMap);


2. Adding elements to the map
------------------------------

Map<Integer, String> employeesMap = new Map<Integer, String>();
System.debug(employeesMap);

employeesMap.put(1, 'Richard');
employeesMap.put(2, 'Monica');
employeesMap.put(3, 'Erlich');
employeesMap.put(4, 'Dinesh');
System.debug(employeesMap);


3. Accessing elements from the map
-----------------------------------

Map<Integer, String> employeesMap = new Map<Integer, String>{
    1 => 'Richard',
    2 => 'Monica',
    3 => 'Erlich',
    4 => 'Dinesh'
};
System.debug(employeesMap);

// System.debug('Employee with id 3 = ' + employeesMap.get(3));
System.debug('Employee with id 10 = ' + employeesMap.get(10));


4. Removing element from the map
-----------------------------------

Map<Integer, String> employeesMap = new Map<Integer, String>{
    1 => 'Richard',
    2 => 'Monica',
    3 => 'Erlich',
    4 => 'Dinesh'
};
System.debug('Initial Map = ' + employeesMap);

System.debug('Removing Employee with Id 4...');
employeesMap.remove(4);

System.debug('Final Map = ' + employeesMap);


5. Checking if the element is present in the map or not
---------------------------------------------------------

Map<Integer, String> employeesMap = new Map<Integer, String>{
    1 => 'Richard',
    2 => 'Monica',
    3 => 'Erlich',
    4 => 'Dinesh'
};
System.debug('Initial Map = ' + employeesMap);

System.debug('Is Employee with id 3 present? => ' + employeesMap.containsKey(3));
System.debug('Is Employee with id 100 present? => ' + employeesMap.containsKey(100));