[SalesForce] How to i match second-last char of a string with RegEx

The option to replace case insensitive regex in java is Pattern.CASE_INSENSITIVE, which can also be specified as (?i)

(http://boards.developerforce.com/t5/Apex-Code-Development/Why-Pattern-CASE-INSENSITIVE-not-detectable/td-p/204337)

String srcStr = '{!id} value {!Id} is not {!ID}';
String replaceToken = '(?i)\\{!id\\}';
System.debug('REPLACEMENT ' + srcStr.replaceAll(replaceToken, ''));
System.assertEquals('  value  is not ', srcStr.replaceAll(replaceToken, ''));

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.