Code used in map advanced methods tutorial on SFDC Stop (https://youtu.be/km2gUwkBN78)

mapadvancedmethods.cls

Map advanced methods:
----------------------

keySet(): Get all keys from a map
-------------------------------------

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

Set<Integer> employeeIds = employeesMap.keySet();
System.debug(employeeIds);

values(): Get all values from a map
--------------------------------------

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

List<String> employeeNames = employeesMap.values();
System.debug(employeeNames);

clear(): Remove all key-value pairs from a map
------------------------------------------------

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

System.debug('Clearing all pairs.....');
employeesMap.clear();

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

isEmpty(): Check if a map is empty
------------------------------------

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

System.debug('Clearing all pairs.....');
employeesMap.clear();

System.debug('Final Map = ' + employeesMap);
System.debug('Is my map empty? => ' + employeesMap.isEmpty());

size(): Get total number of key value pairs from a map
-------------------------------------------------------

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

System.debug('Clearing all pairs.....');
employeesMap.clear();

System.debug('Final Map = ' + employeesMap);
System.debug('Size of the map = ' + employeesMap.size());