Question

我正在尝试创建一个类，当它启动时它启动一个秒表，并且所有时间都将经过的时间写入一个局部变量Elapsed，我有一个数据绑定的Listview。但是，当我使用此代码时，Listview只显示00：00：00.00000001并且永远不会更改。该类的代码是：

namespace project23
{
    public class ActiveEmployee
    {
        public int EmpID { get; set; }
        public string EmpName { get; set; }
        private DateTime date;
        private BackgroundWorker worker;
        public Stopwatch sw;

        public ActiveEmployee(int empID, string empName)
        {
            date = DateTime.Now;
            worker = new BackgroundWorker();
            worker.DoWork += BackgroundWork;
            worker.WorkerReportsProgress = true;

            worker.RunWorkerAsync();
        }

        private TimeSpan elapsed;
        public TimeSpan Elapsed
        {
            get { return elapsed; }
            set
            {
                elapsed = value;
                NotifyPropertyChanged("Elapsed");
            }
        }

        private void BackgroundWork(object sender, DoWorkEventArgs args)
        {
            sw = new Stopwatch();
            sw.Start();
            if(true)
            {
                Elapsed = sw.Elapsed;
            }
        }

        public event PropertyChangedEventHandler PropertyChanged;

        private void NotifyPropertyChanged(String info)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(info));
            }
        }
    }
}

现在使用计时器

using System;
using System.ComponentModel;
using System.Timers;

namespace Eksamen_Januar_2011
{
    public class ActiveEmployee : INotifyPropertyChanged
    {
        public int EmpID { get; set; }
        public string EmpName { get; set; }
        private DateTime startDate;
        private BackgroundWorker worker;
        private Timer timer;

    public ActiveEmployee(int empID, string empName)
    {
        startDate = DateTime.Now;
        worker = new BackgroundWorker();
        worker.DoWork += BackgroundWork;
        timer = new Timer(1000);
        timer.Elapsed += TimerElapsed;
        worker.RunWorkerAsync();
    }

    private TimeSpan elapsed;
    public TimeSpan Elapsed
    {
        get { return elapsed; }
        set
        {
            elapsed = value;
            NotifyPropertyChanged("Elapsed");
        }
    }

    private void BackgroundWork(object sender, DoWorkEventArgs args)
    {
        timer.Start();
    }
    private void TimerElapsed(object sender, ElapsedEventArgs e)
    {
        Elapsed = DateTime.Now - startDate;
    }
    public event PropertyChangedEventHandler PropertyChanged;

    private void NotifyPropertyChanged(String info)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(info));
        }
    }
}

}

Answer 1

您需要实现INotifyPropertyChanged接口。将您的类声明修改为：

public class Employee : System.ComponentModel.INotifyPropertyChanged

请参阅http://msdn.microsoft.com/en-us/library/system.componentmodel.inotifypropertychanged.aspx。

Answer 2

数据绑定和观察更改依赖于更改通知事件;通常*Changed（对于属性*）或INotifyPropertyChanged（尽管可以进行自定义实现）。

Stopwatch没有提供此类内容;你可能最好使用Timer，以便经常更新UI。只需在开始时存储DateTime，并且只要计时器触发计算从那时到现在的偏移量。

Answer 3

拥有if（true）语句有什么意义？你的意思是写（真）吗？

你只是在线程中更新一次经过的时间，然后它就存在..这就是你在表格上看到的那些

已停止使用stopwatched的数据绑定问题

3 个答案: