public void Update(BaseFile baseFile) { if (baseFile == null) { richTextBox.Clear(); return; } if (baseFile.Exists()) { using (FileStream fileStream = new FileStream(baseFile.FilePath, FileMode.Open)) { byte[] buffer = new byte[fileStream.Length]; fileStream.Read(buffer, 0, (int)fileStream.Length); richTextBox.Text = _shiftJis.GetString(buffer); } } }