How to convert List to Map in Salesforce

Here is the simple way to convert list of sobject records to map.

Assigning query result to List:

1. //Assigning return query result to the list.
2. List<Lead> leadList = [SELECT Id, Name FROM Lead];

Assigning query result to Map:

1. //Directly assigning return query result to the map.
2. Map<Id, Lead> leadMap = new Map<Id, Lead>([SELECT Id, Name FROM Lead]);

Converting List to Map:

1. //Converting list to map
2. Map<Id, Lead> mapFromList = new Map<Id, Lead>(leadList);