通过下一个和上一个按钮解析的文本框值数组

本文关键字：文本 数组 下一个 上一个 按钮 | 更新日期: 2023-09-27 18:33:00

我在wform中有一个带有下一个和上一个按钮的表单。我有一个数组中存储的数字范围，并希望通过按钮浏览它们。我需要关于如何做到这一点的帮助和一个可能的例子。我尝试过并到处寻找，但无法得出结论，因为我现在已经撞到了一堵砖墙。

private nextButton_Clicked()
{
    int counter;
    if (counter == 0)
    {
        //content of first page
    } 
}

以上仅适用于第二页，但我需要一些功能性和非重复性的东西。

通过下一个和上一个按钮解析的文本框值数组

private void btnNext_Click(object sender, EventArgs e)
{
    if (pos < someArray.Count() - 1)
    {
        pos++;
        label1.Text = someArray[pos];
    }
}
private void btnPrev_Click(object sender, EventArgs e)
{
    if (pos > 0)
    {
        pos--;
        label1.Text = someArray[pos];
    }
}

'

如果您正在寻找一种可重用的方法来处理此问题，我会将分页逻辑分解为一个单独的类。 解释是内联的。 请务必注意，此实现假定可以安全地多次枚举正在分页的数据。 由于听起来您使用的数据结构是一个数组，因此这应该没问题。

public class Pageable<T>
{
    //This is your array data
    private readonly IEnumerable<T> _data;
    //Number of items per page
    private readonly int _pageSize;
    //The current page (1-indexed)
    private int _currentPage;
    //Calculate Total number of pages based on number of items and user defined page size
    public int TotalPages
    {
        get { return (int)Math.Ceiling((double)_data.Count() / _pageSize); }
    }
    //Constructor to load the data
    public Pageable(IEnumerable<T> data, int pageSize = 10)
    {
        _currentPage = 1;
        _pageSize = pageSize;
        _data = data;
    }
    public IEnumerable<T> NextPage()
    {
        //increment the page
        _currentPage++;
        //make sure that the incremented value does not exceed total pages
        if (_currentPage >= TotalPages) _currentPage = TotalPages;
        return GetPage(_currentPage);
    }
    public IEnumerable<T> PreviousPage()
    {
        //decrement  the page
        _currentPage--;
        //make sure the decremented value is not less than 0
        if (_currentPage <= 0) _currentPage = 0;
        return GetPage(_currentPage);
    }
    public IEnumerable<T> GetCurrentPage()
    {
        return GetPage(_currentPage);
    }
    public IEnumerable<T> GoToPage(int page)
    {
        if (page <= 0)
            throw new Exception("Cannot be less than 1.");
        if (page > TotalPages)
            throw new Exception("Cannot be greater than total number of pages.");
        _currentPage = page;
        return GetPage(_currentPage);
    }
    //The page value is the value that the user would expect.  (1-indexed)
    private IEnumerable<T> GetPage(int page)
    {
        //Correct for 1-indexed page value;
        var pageIndex = page - 1;
        //Use Language Integrated Query (LINQ) to calculate the items we need
        //Skip the first Nth items (pageIndex * _pageSize))
        //Take the next _pageSize items
        return _data.Skip(pageIndex * _pageSize).Take(_pageSize);
    }
}

以下是一些使用 MSTest 的测试，显示了它是如何工作的：

[TestClass]
public class PageableTests
{
    private int[] _data;
    [TestInitialize]
    public void SetUp()
    {
        var initialData = new List<int>();
        for (var i = 1; i < 136; i++)
            initialData.Add(i);
        _data = initialData.ToArray();
    }
    [TestMethod]
    public void CanPageNext()
    {
        var testData = new Pageable<int>(_data);
        var firstPage = testData.GetCurrentPage().ToList();
        Assert.AreEqual(1, firstPage.First());
        Assert.AreEqual(10, firstPage.Last());
        var secondPage = testData.NextPage().ToList();
        Assert.AreEqual(11, secondPage.First());
        Assert.AreEqual(20, secondPage.Last());
    }
    [TestMethod]
    public void ReturnsFirstPageWhenPageIsNegative()
    {
        var testData = new Pageable<int>(_data);
        var firstPage = testData.GetCurrentPage().ToList();
        Assert.AreEqual(1, firstPage.First());
        Assert.AreEqual(10, firstPage.Last());
        var secondPage = testData.PreviousPage().ToList();
        Assert.AreEqual(1, secondPage.First());
        Assert.AreEqual(10, secondPage.Last());
        var thirdPage = testData.PreviousPage().ToList();
        Assert.AreEqual(1, thirdPage.First());
        Assert.AreEqual(10, thirdPage.Last());
    }
    [TestMethod]
    public void CanPreviousPage()
    {
        var testData = new Pageable<int>(_data);
        var firstPage = testData.GetCurrentPage().ToList();
        Assert.AreEqual(1, firstPage.First());
        Assert.AreEqual(10, firstPage.Last());
        var secondPage = testData.NextPage().ToList();
        Assert.AreEqual(11, secondPage.First());
        Assert.AreEqual(20, secondPage.Last());
        testData.NextPage();
        var thirdPage = testData.PreviousPage().ToList();
        Assert.AreEqual(secondPage.First(), thirdPage.First());
        Assert.AreEqual(secondPage.Last(), thirdPage.Last());
        var fourthPage = testData.PreviousPage().ToList();
        Assert.AreEqual(firstPage.First(), fourthPage.First());
        Assert.AreEqual(firstPage.Last(), fourthPage.Last());
    }
    [TestMethod]
    public void CannotExcceedMaxPages()
    {
        var testData = new Pageable<int>(_data);
        for (var i = 0; i < 20; i++)
        {
            testData.NextPage();
        }
        var lastPage = testData.GetCurrentPage().ToList();
        Assert.AreEqual(131, lastPage.First());
        Assert.AreEqual(135, lastPage.Last());
        var nextToLastPage = testData.PreviousPage();
        Assert.AreEqual(121, nextToLastPage.First());
    }
}
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