Error in batch class - not getting the correct time

Question

Getting error in the following lines:

if(Datetime.now().hourgmt() == 16){
                    ev.StartDateTime = Datetime.valueOf(Datetime.now().hourgmt()+24);
                }else{
                    if(Datetime.now().hourgmt()>16){
                        DateTime dd = Datetime.valueOf(Datetime.now().hourgmt()-16);
                        ev.StartDateTime = Datetime.valueOf(Datetime.now().hourgmt()-integer.valueOf(dd));

Batch class:

global class BatchToCreateMeeting implements Database.batchable<sObject>
{
    global Database.QueryLocator start(Database.BatchableContext BC){

        String query = 'SELECT id, name, account.name, OwnerId from Contact where account.name <> null'; 
        return Database.getQueryLocator(query);
    }
    global void execute(Database.BatchableContext BC, List<Contact> listCon){
        List<Event> listEv = new List<Event>();
        system.debug('list of conlst :'+listCon);
        for(Contact con : listCon){
            Event ev = new Event();
            ev.Type = 'Email';
            ev.Subject = 'Todays Meeting';
            ev.DurationInMinutes = 60;
            system.debug('current value :'+Datetime.now().hourgmt());
            system.debug('current value :' +Datetime.valueOf(Datetime.now().hourgmt()+ 24));
            if(Datetime.now().hourgmt() == 16){
                    ev.StartDateTime = Datetime.valueOf(Datetime.now().hourgmt()+24);
                }else{
                    if(Datetime.now().hourgmt()>16){
                        DateTime dd = Datetime.valueOf(Datetime.now().hourgmt()-16);
                        ev.StartDateTime = Datetime.valueOf(Datetime.now().hourgmt()-integer.valueOf(dd));
                    }else{
                        if(Datetime.now().hourgmt()<16){
                        DateTime dd = Datetime.valueOf(16-Datetime.now().hourgmt());
                        ev.StartDateTime = Datetime.valueOf(Datetime.now().hourgmt()+integer.valueOf(dd));
                        }
                    }
            }
            system.debug('Time value start wali :'+ ev.StartDateTime);
            ev.EndDateTime = ev.StartDateTime +1;
            ev.Description  = 'Message will show here';
            ev.OwnerId = con.OwnerId;
            ev.WhoId = con.id;
            listEv.add(ev);
        }
        system.debug('list of listEv :'+ listEv);
        if(listEv.size()>0){
            insert listEv;
        }
    }
    global void finish(Database.BatchableContext BC) {

     }
}

Answer 1

In this line:

ev.StartDateTime = Datetime.valueOf(Datetime.now().hourgmt()+24);

seems that you want to add 1 day. You do not pass a date, so it resets to 1970-01-01. You should change it to:

ev.StartDateTime = Datetime.now().addDays(1);

Also, in

DateTime dd = Datetime.valueOf(Datetime.now().hourgmt()-16);

you should replace it with:

DateTime dd = Datetime.addHours(-16);

It would help, if you write what you want to achieve.