2022.6.4-----leetcode. nine hundred and twenty-nine

  public int numUniqueEmails(String[] emails) {
        Set<String> set=new HashSet<>();// duplicate removal 
        for(String email:emails){
            StringBuilder sb=new StringBuilder();
            // Handle @ Before the string 
            for(int i=0;email.charAt(i)!='@';i++){
                if(email.charAt(i)=='.')
                    continue;
                if(email.charAt(i)=='+')
                    break;
                sb.append(email.charAt(i));
            }
            sb.append(email.substring(email.indexOf('@')));// Add domain name 
            set.add(sb.toString());
        }
        return set.size();
    }