I want to count related Contact in a Account.How can i do this in salesforce Apex Code?

Hi Suraj,

public class AccountProcessor {
static public Integer count;
@future public static void countContacts(Set<Id> AcctId ){
List<Account> Acclist=[select name,AccountNumber from Account where Id in:AcctId];
if(Acclist.size()>0){
for(Account A:Acclist){
count=0;
count=[select count() from Contact where AccountId=:A.Id];
A.Number_of_Contacts__c=count;//[select count() from Contact where AccountId=:A.Id];
update(A);
}
}

where Number_of_Contacts__c is the custom Field on Account which store the Number of Related Contact in Account.

Hope this will Help You