Question

我的列表中填充了文件名。我需要用搜索结果填充另一个列表。此搜索结果必须通过二进制搜索完成，具有下一个规范：关键字可以匹配文件名，或者它的子串（0，key.Length）。例如keyword =“car” 搜索结果=“car.gif”，“carffur.pdf”等，但不是“mobilecar.jar”

我的二元搜索：

    class Search
{
    private const int KEY_NOT_FOUND = -1;

    public static int BinarySearch<T>(List<T> A, T key, IComparer<T> comparer, int imin, int imax)
    {
        // test if array is empty
        if (imax < imin)
            // set is empty, so return value showing not found
            return KEY_NOT_FOUND;
        else
        {
            // calculate midpoint to cut set in half
            int imid = imin + ((imax - imin) / 2);
            int compareResult = comparer.Compare(A[imid], key);
            // three-way comparison
            if (compareResult > 0)
                // key is in lower subset
                return BinarySearch<T>(A, key, comparer,imin, imid - 1);
            else if (compareResult < 0)
                // key is in upper subset
                return BinarySearch<T>(A, key, comparer, imid + 1, imax);
            else
                // key has been found
                return imid;
        }
    }
}

我的比较者课程：

    class SubStringComparison : IComparer<string>
{
    public int Compare(string x, string y)
    {
        if (x.Length > y.Length && x.Substring(0, y.Length).Equals(y))
            return 0;

        return String.Compare(x, y, StringComparison.OrdinalIgnoreCase);
    }
}

用法：

private void backgroundWorkerSearch_DoWork(object sender, DoWorkEventArgs e)
    {
        SearchForFiles();
    }

    private void SearchForFiles()
    {
        List<string> files = listBoxFiles.Items.OfType<string>().ToList();
        searchResults = new List<string>();
        listBoxFiles.Dispatcher.Invoke(new Action(delegate()
            {
                while (true)
                {
                    int index = Search.BinarySearch<string>(files, textBoxFileToSearch.Text, new SubStringComparison(), 0, files.Count - 1);
                    if (index == -1)
                        break;
                    else
                        searchResults.Add(files[index]);
                }
            }));
    }

Answer 1

-1你的家庭作业哪部分有问题？是二元搜索吗？是文件名的选择吗？是BackgroundWorker没有按预期工作吗？

我发现你在BackgroundWorker上遇到了一些问题，看来你是在BackgroundWorker线程中从UI中选择一个文件列表，然后创建一个将在主线程中运行的Action，这是一个很奇怪的方法。它

正确的方法是：

public void button1_Click(object sender)
{
    List<string> files = listBoxFiles.Items.OfType<string>().ToList();
    string key = textBoxFileToSearch.Text;
    backgroundWorkerSearch.RunWorkerAsync(new Tupple<List<string>,string>(files, key));
}

void backgroundWorkerSearch_DoWork(object sender, DoWorkEventArgs e)
{
     var state = e.Argument as Tupple<List<string>,string>;
     List<string> files = state.Item1;
     string key = state.Item2;
     // You can now access the needed data.
     List<string> searchResult = new List<string>();
     // ...
     e.Result = searchResult;
}

void backgroundWorkerSearch_RunWorkerCompleted(RunWorkerCompletedEventArgs e)
{
     List<string> searchResult = e.Result;
     // Show result in the UI thread.
}

使用二进制搜索填充列表

1 个答案: