How to add days with Date field?

Question

I have one date field called "Billing date" and one Number Field called "Billing Delay". I want to update one Date field "DueDate" which computes "Billing date"+"Billing Delay"

for Eg:

"Billing date"=15.11.2016 "Billing Delay"=10 "DueDate"=25.11.2016

While Computation It will Exclude the Saturday and Sunday.

How to achieve this ?

Apex:

for(BEV_BillingEvent__c BillingEvent:lstBillingEvent) {
    Date d=BillingEvent.Billingdate__c;
    Integer i=BillingEvent.BillingDelay__c;  
}

Answer 1

Try the below code. Its much simpler and covers your requirement (I believe).

    for(BEV_BillingEvent__c BillingEvent:lstBillingEvent) 

{

    Datetime dt = DateTime.newInstance(BillingEvent.Billingdate__c, 3, 3, 3,0);
    //system.debug('dt** = '+ dt);

        for (Integer i = 1; i <= BillingEvent.BillingDelay__c;) {
          dt = dt.addDays(1);
          system.debug('dt = '+ dt+dt.format('EEE'));
          if(dt.format('EEE') != 'Sun' && dt.format('EEE') != 'Sat') i++;
        }
}

Answer 2

addDays(additionalDays) Adds the specified number of additional days to a Date.

Date methods

you can simply use addDays method

for(BEV_BillingEvent__c BillingEvent:lstBillingEvent) 
{
      Date d=BillingEvent.Billingdate__c.addDays(BillingEvent.BillingDelay__c);

}

For excluding the Saturday and Sunday use below method, You need to pass the start and end date.

this will return exact days in number with excluding Saturday and Sunday.

once you get that number. Add those many days in billing date.

public static Integer daysBetweenExcludingWeekends(Datetime startDate, Datetime endDate) {
    Integer i = 0;

    while (startDate < endDate) {
        if (startDate.format('E') != 'Sat' && startDate.format('E') != 'Sun') {
            i++;
        }
        startDate = startDate.addDays(1);
    }

    return i;
}

Check this answer for more options https://salesforce.stackexchange.com/a/5355/18731