The Matcher class end method returns the position in the match string after the last character that was matched. You would use this when you are parsing a string and want to do additional work with it after you have found a match, such as find the next match.
In regular expression syntax, ? means match once or not at all, and + means match 1 or more times.
In the following example, the string passed in with the Matcher object matches the pattern since (a(b)?) matches the string 'ab' - 'a' followed by 'b' once. It then matches the last 'a' - 'a' followed by 'b' not at all.
pattern myPattern = pattern.compile('(a(b)?)+'); matcher myMatcher = myPattern.matcher('aba'); System.assert(myMatcher.matches() && myMatcher.hitEnd()); // We have two groups: group 0 is always the whole pattern, and group 1 contains // the substring that most recently matched--in this case, 'a'. // So the following is true: System.assert(myMatcher.groupCount() == 2 && myMatcher.group(0) == 'aba' && myMatcher.group(1) == 'a'); // Since group 0 refers to the whole pattern, the following is true: System.assert(myMatcher.end() == myMatcher.end(0)); // Since the offset after the last character matched is returned by end, // and since both groups used the last input letter, that offset is 3 // Remember the offset starts its count at 0. So the following is also true: System.assert(myMatcher.end() == 3 && myMatcher.end(0) == 3 && myMatcher.end(1) == 3);
In the following example, email addresses are normalized and duplicates are reported if there is a different top-level domain name or subdomain for similar email addresses. For example, john@fairway.smithco is normalized to john@smithco.
class normalizeEmailAddresses{ public void hasDuplicatesByDomain(Lead[] leads) { // This pattern reduces the email address to 'john@smithco' // from 'john@*.smithco.com' or 'john@smithco.*' Pattern emailPattern = Pattern.compile('(?<=@)((?![\\w]+\\.[\\w]+$) [\\w]+\\.)|(\\.[\\w]+$)'); // Define a set for emailkey to lead: Map<String,Lead> leadMap = new Map<String,Lead>(); for(Lead lead:leads) { // Ignore leads with a null email if(lead.Email != null) { // Generate the key using the regular expression String emailKey = emailPattern.matcher(lead.Email).replaceAll(''); // Look for duplicates in the batch if(leadMap.containsKey(emailKey)) lead.email.addError('Duplicate found in batch'); else { // Keep the key in the duplicate key custom field lead.Duplicate_Key__c = emailKey; leadMap.put(emailKey, lead); } } } // Now search the database looking for duplicates for(Lead[] leadsCheck:[SELECT Id, duplicate_key__c FROM Lead WHERE duplicate_key__c IN :leadMap.keySet()]) { for(Lead lead:leadsCheck) { // If there's a duplicate, add the error. if(leadMap.containsKey(lead.Duplicate_Key__c)) leadMap.get(lead.Duplicate_Key__c).email.addError('Duplicate found in salesforce(Id: ' + lead.Id + ')'); } } } }