Do not add object to object list if already exists - salesforce

Question

I am doing a fairly simple query for contact records using dynamic soql using the following method:
public PageReference contactSearch() {
contactResultSetSize = 0;
if(!String.isEmpty(firstname) || !String.isEmpty(lastname) || !String.isEmpty(company)) {
string soql = 'Select firstname, lastname, account.Name, account.BillingStreet, account.BillingCity, account.BillingState, account.BillingPostalCode From Contact';
String whereClause = '';
if(!String.isEmpty(firstname)) {
whereClause = ' Where firstname like \'%' + firstname + '%\'';
}
if(!String.isEmpty(lastname)) {
if(!String.isEmpty(firstname)) {
whereClause += ' AND lastname like \'%' + lastname + '%\'';
}
else {
whereClause = ' Where lastname like \'%' + lastname + '%\'';
}
}
if(!String.isEmpty(company)) {
if(!String.isEmpty(firstname) || !String.isEmpty(lastname)) {
whereClause += ' AND account.Name like \'%' + company + '%\'';
}
else {
whereClause = ' Where account.Name like \'%' + company + '%\'';
}
}
soql = soql + whereClause;
List<Contact> searchResults = Database.query(soql);
contactResultSetSize = searchResults.size();
if(contactLinesForPage == null) {
contactLinesForPage = new List<ContactWrapper>();
}
for(Contact c : searchResults) {
contactLinesForPage.add(new ContactWrapper(contactLinesForPage.size(), c, ''));
}
}
return null;
}
I am using a wrapper class and contactLinesForPage is a list of my wrapper object:
public List<ContactWrapper> contactLinesForPage {get; set;}
As a user does multiple searches, I don't want to re-add records to the searchResults list. How can I check if a record already exists in my object so I don't have duplicate records returned in the search?
Thanks for any help.

Answer 1

Or you could use a map. Add the ContactWrapper objects to the map. The key to the map is an id. If they add a duplicate contact it will simply overwrite the one already there. Your code would simply be
aMap.put(cw.id, cw); // one line eliminates duplicates.
When you want the list of ContactWrappers, simply return aMap.values();
If you want to abstract the behavior of maintaining the collection of Contacts, create a ContactCollection class and hide the implementation in there. This would provide something more reusable as well as a good pattern for similar situations.

Answer 2

Just add a check if contactLinesForPage allready contains this contact. Something like this:
for(Contact c : searchResults) {
Boolean toInsert = true;
for(ContactWrapper cw : contactLinesForPage){
if(cw.contact.Id == c.Id){
toInsert=false;
}
}
if(toInsert){
contactLinesForPage.add(new ContactWrapper(contactLinesForPage.size(), c, ''));
}
}