C#

public EnglishDataBase()
        {
            MultiThread mt = new MultiThread();

            englishCapLetter = new Dictionary<char, int>();
            englishSmallLetter = new Dictionary<char, int>();

            Thread t1 = new Thread(new ThreadStart(mt.fillCaps(ref englishCapLetter))));
            Thread t2 = new Thread(new ThreadStart(mt.fillUnCaps(ref englishSmallLetter)));
            

            t1.Start();
            t2.Start();
            t1.Join();
            t2.Join();
        }

public void fillCaps(ref Dictionary<char, int> englishCapLetter)
        {
            while (!sr1.EndOfStream)
            {
                string letter = sr1.ReadLine();
                englishCapLetter.Add(char.Parse(letter.ToUpper()), char.Parse(letter.ToUpper()));
            }
        }

        public void fillUnCaps(ref Dictionary<char, int> englishSmallLetter)
        {
            while (!sr2.EndOfStream)
            {
                string letter = sr2.ReadLine();
                englishSmallLetter.Add(char.Parse(letter.ToLower()), char.Parse(letter.ToLower()));
            }
        }