StreamReader＆＃34;不能像方法一样使用＆＃34;

Question

我得到了错误＆＃34; CS1955 - 不可调用的成员＆＃39; StreamReader＆＃39;不能像方法一样使用。

if (openFileDialog1.ShowDialog() == DialogResult.OK)
        {
            //Definir o objeto para leitura do arquivo
            System.IO.StreamReader leitor = System.IO.StreamReader(openFileDialog1.FileName);
            //Descarregar o conteúdo do arquivo na richTextBox1
            textoRichTextBox.Rtf = leitor.ReadToEnd();
            //Fechar o objeto de leitura do arquivo
            leitor.Close();
        }

Answer 1

using(var leitor = new System.IO.StreamReader(openFileDialog1.FileName)) {
    textoRichTextBox.Rtf = leitor.ReadToEnd();
}

或只是：

textoRichTextBox.Rtf = File.ReadAllText(openFileDialog1.FileName);