[SalesForce] using regex in replaceAll to replace multiple char in one go

Ultimately, the code I came up with for validation looked something like what's below:

list<Event> ToInsert = new list<Event>();
Date ClosDt;
Integer ClsDay; 
Integer ClsMnth;
Integer ClsYear; 
String sClsDay; 
String sClsMnth;
String sClsYear; 
String StrtTmDt;
Integer plnMns;
String endTm;
String endDtTm;
String notes;
Pattern TimePttrn = Pattern.compile('((([1])([0-2])|(([0])([1-9])))(\\u003A)(([0-5])([0-9]))(\\s)(([AP])([M])))'); // hh:mm a


// The initial section below is to use Event_Notes__c to track any error messages 
// related to the start time and return them for correction while allowing 
// successful creation of the event. It existed before we went to a picklist.

try{
    If (opp.Event_Notes__c == null) notes = 'None';

    }catch(NullPointerException e){

    notes = 'None';

    } 

    notes = opp.Event_Notes__c;

try{
    opp.Event_Start_Time_Pik__c.normalizeSpace();

    }catch(NullPointerException e){

        if (notes == 'None') {

            notes = 'Error A1 processing Start Time!!! Check for correct time and resubmit form.';

            opp.Event_Start_Time_Pik__c = '12:00 AM';

        } else{

            notes = 'Error A2 processing Start Time!!! Check for correct time and resubmit form.'+ notes;

            opp.Event_Start_Time_Pik__c = '12:00 AM'; 

        }

    } // End try/catch block

// Do time pattern and match validation

Matcher m = TimePttrn.matcher(opp.Event_Start_Time_Pik__c);
boolean hasMatch = m.matches();
strtTm = m.group(0);

opp.Event_Notes__c = notes;

// Assemble StartTimeDate and Calculate Planned Mins

ClosDt = opp.CloseDate;
ClsDay = ClosDt.day();

if(ClsDay >= 1 && ClsDay <= 9){ 

sClsDay = '0' + String.ValueOf(ClsDay);

} else {

sClsDay = String.ValueOf(ClsDay);

}

ClsMnth = ClosDt.month();

if(ClsMnth >=0 && ClsMnth <= 9){ 

   sClsMnth = '0' + String.ValueOf(ClsMnth);

   } else {

   sClsMnth = String.ValueOf(ClsMnth);

   }

ClsYear = ClosDt.year();

sClsYear = String.ValueOf(ClsYear);    

StrtTmDt = sClsMnth + '/' + sClsDay + '/' + sClsYear + ' ' + strtTm;

Later in the code when creating the event:

Event e = New Event(StartDateTime = DateTime.parse(StrtTmDt), ActivityDateTime = DateTime.parse(StrtTmDt), EndDateTime = (DateTime.parse(StrtTmDt)).addMinutes(plnMns), DurationInMinutes = plnMns, Subject = EvtSubjct, OwnerId = opp.Owner.Id, WhatId = opp.Id, WhoId = opp.Customer_Contact__r.Id, Description = Descr1 + Descr2 + Descr3 + Descr5 + Descr6 + Descr7 );

I wound up doing a lot of string method and regex testing bits of code in the Developer Console and creating some string test classes before I managed to get all of this to work satisfactorily. I learned a great deal in the process. I hope others find this of use as until there's a "true" Time method other than the Salesforce System Time, this will continue to be an issue we'll all need to deal with on occasion.

I think text area uses newline only ('\n'). So a replace like this:

repairComm.replaceAll('\n', '\\\\n')

will result in each newline character replaced with the two characters '\' and 'n' which is what is required in JSON. (The double escaping is required because of how regular expressions handle backslash.)

But it is safer to put this string through one of the Apex JSON methods as other escaping may also be needed (such as double quotes):

repairComm = JSON.serialize(repairComm);

But what you have in your text area is a mix of valid and invalid JSON so hard to cleanup without double escaping. If the JSON has fixed structure, it would be simpler to provide separate text fields for the multi-line input parts and combine them programmatically so the right escaping is applied where it is needed and not applied where it is not.