Whats the differece between them?

Question

Can anyone explain me the difference in this code?
Why do we an if(!) condition? What are the best reasons to go for this kind of code?
What is wrong with my breat label statement below?
List<SalesOrder>listReturned = new ArrayList<SalesOrder>();
Set <String>ids = new HashSet<String>();
if (ids.contains(so.getTempOrderNumber())) break label379;//this part of code displays an error
        label379: list.add(so);
if (!ids.contains(so.getTempOrderNumber()))
list.add(so);
}

Answer 1

I need to know if the two versions of code are equal?
I have read the tutorial you said(i.e javaworld nuts and bolts)? I could not understand this codeeven after reading that?
Question:
is if((!(some expression)))&&((!(!(some expression)))
is similar to
if(expression||expression)?
What role parenthesis in this expression signify?
if (accounts.containsKey(type)) {
for (ErpQADBase rec : accounts.get(type)) {
if (rec.getAccountNumber().equals(accountId) || rec.getTemporaryAccountNumber().equals(accountId)) {**
   return rec;
} else {
     accounts.put(type, new ArrayList<ErpQADBase>());**
if (accounts.containsKey(type))
        for (localIterator = ((List)accounts.get(type)).iterator(); localIterator.hasNext(); )
rec = (ErpQADBase)localIterator.next();
  if ((!(rec.getAccountNumber().equals(accountId))) && (!(rec.getTemporaryAccountNumber().equals accountId))))      
    break label92;
       label92: return rec;
      else {
        accounts.put(type, new ArrayList());
      }