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Abilash Kosigi 8Abilash Kosigi 8 

Retrieving Field values from a Map

querystring = select <all fields> of Car__C

List<Car__c> L = Database.query(querystring);
    Map<Id, Car__c> m = new Map<Id, Car__c>(L);

for (Car__c field : m.values())
{
    <Car_NO> (Here it should display car no of each car.
     Similaryly, any field value of each record needs to be diplayed.
}

Please help with this.
Peter_sfdcPeter_sfdc
When you call m.values() the map ceases to be an issue. In your for loop you would do: 

for (Car__c aCar : m.values())
{
    System.debug(aCar.field_name__c); // output the value of this field in this car record to the log
}
Vinit_KumarVinit_Kumar
I don't understand the reason why you are adding the List which is being queried and putting to map and then using map.Values() which would return same  List of records .

Can't we use the same List which is being queried ??
James LoghryJames Loghry
Vinit is correct, using your code example, there's little or no need for a list.  In fact, you could just do something similar to:

for(Car__c car : [Select fields of Car__c]){
    System.debug('Car name: ' + carName);
}

This would give you a similar result to map.values() in Peter's example, but since maps are unordered, Peter's list is unordered, where as the example above, using a list, is ordered.

In the map case, in addition to Peter's example, you could iterate over keySet(), and then use .get(key) to get your Car value.  An example of this is below:

Map<Id,Car__c> carMap = new Map<Id,Car__c>([Select Id,Name From Car__c]);

for (Id carId : carMap.keySet()){
    Car__c currentCar = carMap.get(carId);
    System.debug('Car name: ' +  currentCar.Name);
}