我正在开发VS2015社区的UWP应用程序，我已经制作了一个候选人类和另一个候选人类CandidateManager。在CandidateManager类中，我创建了一个方法getCandidateByCategory，以按类别编号和序列号对候选进行排序。我在ScienceAndITClub.Xaml.cs页面上调用了该方法，但现在我在检索过滤项目的name属性时遇到问题（将其设置为RBcand1 radiobutton的内容），＆＃下面的红线是＃ 39;＆＃39;它显示错误＆＃34;运营商＆＃39;。＆＃39;不能应用于＆＃39; void＆＃39;＆＃34;类型的操作数。此外，总是只有一个具有特定类别编号和序列号的候选人。
这是Science＆amp; ITClub.Xaml.cs：
public sealed partial class ScienceAndITClub : Page
{
private ObservableCollection<Candidate> Candidates;
public ScienceAndITClub()
{
this.InitializeComponent();
CandidateManager.GetAllCandidates(Candidates);
var v = new Candidate();
v = (CandidateManager.GetCandidatesByCategory(Candidates, CandidateCategoryNo.I, CandidateSNo.I).ToList<Candidate>);
string cand1name = v.Name;
RBcand1.Content = cand1name;
}
private void NextButton_Click(object sender, RoutedEventArgs e)
{
}
}
这里是候选类的代码，即Candidate.cs：
public class Candidate
{
public int VoteCount { get; set; }
public string Name { get; set; }
public string Category { get; set; }
public CandidateSNo S_no { get; set; }
public CandidateCategoryNo Category_no { get; set; }
}
public enum CandidateCategoryNo
{
I,
II,
III,
IV,
V,
VI
}
public enum CandidateSNo
{
I,
II,
III
}
这里是CandidateManager类的代码，即CandidateManager.cs：
class CandidateManager { public static void GetAllCandidates(ObservableCollection<Candidate> candidates) { var allCandidates = getCandidate(); candidates.Clear(); allCandidates.ForEach(p => candidates.Add(p)); } public static void GetCandidatesByCategory(ObservableCollection<Candidate> candidates, CandidateCategoryNo candidateCategory, CandidateSNo Sno) { var allCandidates = getCandidate(); var filteredCandidates = allCandidates.Where(p => p.Category_no == candidateCategory).ToList(); filteredCandidates = allCandidates.Where(p => p.S_no == Sno).ToList(); candidates.Clear(); filteredCandidates.ForEach(p => candidates.Add(p)); } private static List<Candidate> getCandidate() { var _candidate = new List<Candidate>(); _candidate.Add(new Candidate() { S_no = CandidateSNo.I, Category_no = CandidateCategoryNo.I, VoteCount = 0, Category = "Science and IT Club", Name = "A" }); _candidate.Add(new Candidate() { S_no = CandidateSNo.II, Category_no = CandidateCategoryNo.I, VoteCount = 0, Category = "Science and IT Club", Name = "B" }); _candidate.Add(new Candidate() { S_no = CandidateSNo.III, Category_no = CandidateCategoryNo.I, VoteCount = 0, Category = "Science and IT Club", Name = "C" }); _candidate.Add(new Candidate() { S_no = CandidateSNo.I, Category_no = CandidateCategoryNo.II, VoteCount = 0, Category = "Dance Club", Name = "D" }); _candidate.Add(new Candidate() { S_no = CandidateSNo.II, Category_no = CandidateCategoryNo.II, VoteCount = 0, Category = "Dance Club", Name = "E" }); _candidate.Add(new Candidate() { S_no = CandidateSNo.III, Category_no = CandidateCategoryNo.II, VoteCount = 0, Category = "Dance Club", Name = "F" }); _candidate.Add(new Candidate() { S_no = CandidateSNo.I, Category_no = CandidateCategoryNo.III, VoteCount = 0, Category = "Music Club", Name = "G" }); _candidate.Add(new Candidate() { S_no = CandidateSNo.II, Category_no = CandidateCategoryNo.III, VoteCount = 0, Category = "Music Club", Name = "H" }); _candidate.Add(new Candidate() { S_no = CandidateSNo.III, Category_no = CandidateCategoryNo.III, VoteCount = 0, Category = "Music Club", Name = "I" }); _candidate.Add(new Candidate() { S_no = CandidateSNo.I, Category_no = CandidateCategoryNo.IV, VoteCount = 0, Category = "Social Service Club", Name = "J" }); _candidate.Add(new Candidate() { S_no = CandidateSNo.II, Category_no = CandidateCategoryNo.IV, VoteCount = 0, Category = "Social Service Club", Name = "K" }); _candidate.Add(new Candidate() { S_no = CandidateSNo.III, Category_no = CandidateCategoryNo.IV, VoteCount = 0, Category = "Social Service Club", Name = "L" }); _candidate.Add(new Candidate() { S_no = CandidateSNo.I, Category_no = CandidateCategoryNo.V, VoteCount = 0, Category = "Sports Club", Name = "M" }); _candidate.Add(new Candidate() { S_no = CandidateSNo.II, Category_no = CandidateCategoryNo.V, VoteCount = 0, Category = "Sports Club", Name = "N" }); _candidate.Add(new Candidate() { S_no = CandidateSNo.III, Category_no = CandidateCategoryNo.V, VoteCount = 0, Category = "Sports Club", Name = "O" }); _candidate.Add(new Candidate() { S_no = CandidateSNo.I, Category_no = CandidateCategoryNo.VI, VoteCount = 0, Category = "School Captain", Name = "P" }); _candidate.Add(new Candidate() { S_no = CandidateSNo.II, Category_no = CandidateCategoryNo.VI, VoteCount = 0, Category = "School Captain", Name = "Q" }); _candidate.Add(new Candidate() { S_no = CandidateSNo.III, Category_no = CandidateCategoryNo.VI, VoteCount = 0, Category = "School Captain", Name = "R" }); return _candidate; } }
此外，在这个节目中，我将采取候选人＆＃39;作为用户输入的名称（我还没有将其设计为函数，所以我把所有名称都只是字母表），所以请你告诉我如何将文本框中的输入转换为候选人的name属性。
希望你能帮忙...谢谢，祝你有愉快的一天！ :)
答案 0 :(得分：0)
您正在传递集合对象并在“过滤”中修改它。所以，在你的情况下，你可以调用方法，这将改变ScienceAndITClub页面的集合 - 所以从中读取。如果你使用.FirstOrDefault（），它将为你提供第一个条目（你只期望一个），如果集合中没有任何内容，则为null。
这应该解决您的错误问题。但是，一旦开始获取数据，您将看到更多问题。
public sealed partial class MainPage : Page
{
private ObservableCollection<Candidate> Candidates = new ObservableCollection<Candidate>();
public MainPage()
{
this.InitializeComponent();
CandidateManager.GetAllCandidates(Candidates);
//this line alters the Candidates collection
CandidateManager.GetCandidatesByCategory(Candidates, CandidateCategoryNo.I, CandidateSNo.I);
//now that the method is done, you can use the Candidates collection to get the results
var v = Candidates.FirstOrDefault(); //will get first candidate, or null if collection is empty
string cand1name = v.Name;
RBcand1.Content = cand1name;
}
}
<强>更新
我有一点时间吃午饭，所以我把你可以考虑的东西放在一起，当你开发你的项目时。让CandidateManager管理候选者并成为数据的来源。在真实世界的应用程序中，我会去MVVM路由并创建存储库和服务层......但这应该让你开始。如果您的应用程序需要，请更改为ObservableCollection。
public class CandidateManager
{
//first time CandidateManager is used, it will populate backing store
static CandidateManager()
{
//initialize data collection
Candidates = new List<Candidate>();
GetCandidateData().ForEach(p => Candidates.Add(p));
}
/// <summary>
/// Backing Store
/// </summary>
private static List<Candidate> Candidates { get; set; }
/// <summary>
/// Returns all candidates
/// </summary>
/// <returns></returns>
public static List<Candidate> GetAllCandidates()
{
return Candidates;
}
/// <summary>
/// Returns all candidates for a specified category
/// </summary>
/// <param name="candidateCategory"></param>
/// <returns></returns>
public static List<Candidate> GetCandidatesByCategory(CandidateCategoryNo candidateCategory)
{
return Candidates.Where(c => c.Category_no == candidateCategory).ToList();
}
/// <summary>
/// Returns specific candidate based on unique category/sno combination.
/// Returns null if no match
/// </summary>
/// <param name="candidateCategory"></param>
/// <param name="Sno"></param>
/// <returns></returns>
public static Candidate GetCandidateByCategoryAndSno(CandidateCategoryNo candidateCategory, CandidateSNo Sno)
{
return Candidates.Where(c => c.S_no == Sno && c.Category_no == candidateCategory).FirstOrDefault();
}
/// <summary>
/// data creation
/// </summary>
/// <returns></returns>
private static List<Candidate> GetCandidateData()
{
var _candidate = new List<Candidate>();
_candidate.Add(new Candidate() { S_no = CandidateSNo.I, Category_no = CandidateCategoryNo.I, VoteCount = 0, Category = "Science and IT Club", Name = "A" });
_candidate.Add(new Candidate() { S_no = CandidateSNo.II, Category_no = CandidateCategoryNo.I, VoteCount = 0, Category = "Science and IT Club", Name = "B" });
_candidate.Add(new Candidate() { S_no = CandidateSNo.III, Category_no = CandidateCategoryNo.I, VoteCount = 0, Category = "Science and IT Club", Name = "C" });
_candidate.Add(new Candidate() { S_no = CandidateSNo.I, Category_no = CandidateCategoryNo.II, VoteCount = 0, Category = "Dance Club", Name = "D" });
_candidate.Add(new Candidate() { S_no = CandidateSNo.II, Category_no = CandidateCategoryNo.II, VoteCount = 0, Category = "Dance Club", Name = "E" });
_candidate.Add(new Candidate() { S_no = CandidateSNo.III, Category_no = CandidateCategoryNo.II, VoteCount = 0, Category = "Dance Club", Name = "F" });
_candidate.Add(new Candidate() { S_no = CandidateSNo.I, Category_no = CandidateCategoryNo.III, VoteCount = 0, Category = "Music Club", Name = "G" });
_candidate.Add(new Candidate() { S_no = CandidateSNo.II, Category_no = CandidateCategoryNo.III, VoteCount = 0, Category = "Music Club", Name = "H" });
_candidate.Add(new Candidate() { S_no = CandidateSNo.III, Category_no = CandidateCategoryNo.III, VoteCount = 0, Category = "Music Club", Name = "I" });
_candidate.Add(new Candidate() { S_no = CandidateSNo.I, Category_no = CandidateCategoryNo.IV, VoteCount = 0, Category = "Social Service Club", Name = "J" });
_candidate.Add(new Candidate() { S_no = CandidateSNo.II, Category_no = CandidateCategoryNo.IV, VoteCount = 0, Category = "Social Service Club", Name = "K" });
_candidate.Add(new Candidate() { S_no = CandidateSNo.III, Category_no = CandidateCategoryNo.IV, VoteCount = 0, Category = "Social Service Club", Name = "L" });
_candidate.Add(new Candidate() { S_no = CandidateSNo.I, Category_no = CandidateCategoryNo.V, VoteCount = 0, Category = "Sports Club", Name = "M" });
_candidate.Add(new Candidate() { S_no = CandidateSNo.II, Category_no = CandidateCategoryNo.V, VoteCount = 0, Category = "Sports Club", Name = "N" });
_candidate.Add(new Candidate() { S_no = CandidateSNo.III, Category_no = CandidateCategoryNo.V, VoteCount = 0, Category = "Sports Club", Name = "O" });
_candidate.Add(new Candidate() { S_no = CandidateSNo.I, Category_no = CandidateCategoryNo.VI, VoteCount = 0, Category = "School Captain", Name = "P" });
_candidate.Add(new Candidate() { S_no = CandidateSNo.II, Category_no = CandidateCategoryNo.VI, VoteCount = 0, Category = "School Captain", Name = "Q" });
_candidate.Add(new Candidate() { S_no = CandidateSNo.III, Category_no = CandidateCategoryNo.VI, VoteCount = 0, Category = "School Captain", Name = "R" });
return _candidate;
}
}
然后，在您的UI代码中，只需使用管理器来检索数据。
public MainPage()
{
this.InitializeComponent();
var c = CandidateManager.GetCandidateByCategoryAndSno(CandidateCategoryNo.II, CandidateSNo.II);
RBcand1.Content = c?.Name;
}