StreamWriter不关闭，将不会写入到文件中

    using System.Collections;
    using System.Text;

    namespace 字典排序
    {
    public partial class Form1 : Form
    {
    string file = "";
    public Form1()
    {
    InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
    progressBar1.Value = 0;
    if (openFileDialog1.ShowDialog() == DialogResult.OK)
    {
    file = openFileDialog1.FileName;
    label1.Text = file;
    }
    }

    private void button2_Click(object sender, EventArgs e)
    {
    if (File.Exists(file))
    {

    FileStream fs = new FileStream(file, FileMode.Open);
    StreamReader sr = new StreamReader(fs);

    List
        gg = new List
            ();
            String sb;
            while ((sb = sr.ReadLine()) != null)
            {
            gg.Add(sb);
            }
            gg.Sort();
            sr.Close();
            fs.Close();
            progressBar1.Value = 50;
            fs = new FileStream(file, FileMode.Create);
            StreamWriter sw = new StreamWriter(fs);
            foreach (object obj in gg)
            {
            sw.WriteLine(obj.ToString());
            }
            sw.Close();
            fs.Close();
            progressBar1.Value = 100;
            MessageBox.Show("Finished");
            }
            else
            {
            label1.Text = "";
            MessageBox.Show("请选择文本文档！");
            }
            }

            private void Form1_Load(object sender, EventArgs e)
            {
            label1.Text = "";
            }
            }
            }