●Mapの利用方法:
Map<String,String> myMap = new Map<String,String>{‘A1’=>’a1’,’A2’=>’a2’…);
●Map2
Map<Id,Account> myMap = new Map<Id,Account>([Select id,name from Account]);
●Map3
Map<Id,Account> myMap = new Map<Id,Account>([Select id,name from Account]);
List<Id> myId = New List<Id>(myMap.keySet());