问题描述
我想将“Current”属性添加到我的列表类 VolumeList。 这是我的代码：
class Volume
{
private string name;
private string color;
private bool has_segment;
public Volume(string Name,string color,bool has_segment)
this.name = name;
this.color = color;
this.has_segment = has_segment;
public string Name
{
get { return name; }
set { name = value; }
}
public string Color
{
get { return color; }
set { color = value; }
}
public bool HasSegment
{
get { return has_segment; }
set { has_segment = value; }
}
public static ROOTList<Volume> VolumeList{ get; set; } = new ROOTList<Volume>();
}
public class ROOTList<T> : List<T>
{
public T Last
{
get
{
return this[this.Count - 1];
}
set
{
this[this.Count - 1] = value;
}
}
public T First
{
get
{
return this[0];
}
set
{
this[0] = value;
}
}
public T Current
{
}
}
Volume.VolumeList.Current.Name (I get the name of the current volume)
Volume.VolumeList.Current.Name = "test" (I set the name "test" to the current volume).
请问您有什么解决办法吗？
最好的问候
解决方法
关于如何执行此操作有几个选项。由于您刚刚开始，我会说使用选项 1，因为这要简单得多。
选项 1：基本使用 LINQ
下面是一个 Volume 类和一个 Main 方法，显示了用法示例。您可以使用 Linq 获取卷列表中的第一个/最后一个项目，然后您可以使用 volumes[i] 设置列表中各个项目的属性，其中 i 是列表中项目的索引.
您还可以使用 Linq 查找基于 Color、Name、HasVolume 的特定卷，然后使用 foreach 循环更改每个卷的属性。>
有关 LINQ 的更多信息在这里：https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/concepts/linq/。
看看下面的例子：
using System.Collections.Generic;
using System.Linq;
namespace ConsoleApp1
{
internal class Program
{
private static void Main(string[] args)
{
var volumes = new List<Volume>();
var volume1 = new Volume("vol1","red",true);
var volume2 = new Volume("vol2",true);
volumes.Add(volume1); //adds the first volume
volumes.Add(volume2); //adds the second volume
var lastVolume = volumes.First(); //gets the first volume
var firstVolume = volumes.Last(); //gets the last volume
volumes[0].Color = "blue"; //sets the first volume color to blue
volumes[1].Color = "green"; //sets the second volume color to green
// set all green volumes to purple
var greenVolumes = volumes.Where(v => v.Color == "green");
foreach (var greenVolume in greenVolumes)
{
greenVolume.Color = "purple";
}
}
}
public class Volume
{
public string Name { get; set; }
public string Color { get; set; }
public bool HasSegment { get; set; }
public Volume(string name,string color,bool hasSegment)
{
Name = name;
Color = color;
HasSegment = hasSegment;
}
}
}
选项 2：更高级的使用迭代器模式
看看这里的迭代器模式：https://www.dofactory.com/net/iterator-design-pattern。
基本上，它允许您通过选择 MoveNext()、Last、First 和 Current 来逐步浏览列表。我添加了一个 _current 字段，用于跟踪您正在使用的项目。它与集合/列表的索引有关。
using System.Collections.Generic;
namespace WebApplication1.Sandbox
{
public class Volume
{
public string Name { get; set; }
public string Color { get; set; }
public bool HasSegment { get; set; }
public Volume(string name,bool hasSegment)
{
Name = name;
Color = color;
HasSegment = hasSegment;
}
}
public class Iterator<T>
{
private readonly List<T> _items;
private int _index;
public T Last
{
get => _items[_items.Count - 1];
set => _items[_items.Count - 1] = value;
}
public T First
{
get => _items[0];
set => _items[0] = value;
}
public T Current
{
get => _items[_index];
set => _items[_index] = value;
}
public Iterator(List<T> items)
{
_items = items;
}
public bool MoveNext()
{
if (_index == _items.Count - 1)
{
return false;
}
else
{
_index++;
return true;
}
}
}
}
现在你可以像在这个单元测试中一样使用它：
[Fact]
public void VolumeIteratorGetsNextThenSetsCurrentByProperty()
{
var sut = new Iterator<Volume>(_volumes);
sut.MoveNext();
sut.Current.Name = "vol2modifiedAgain";
Assert.Equal("vol2modifiedAgain",sut.Current.Name);
}
单元测试在这里：
using System.Collections.Generic;
using WebApplication1.Sandbox;
using Xunit;
namespace WebApplication1.Tests
{
public class VolumeIteratorTests
{
private List<Volume> _volumes => new List<Volume>()
{
new Volume("vol1","green",true),new Volume("vol2",true)
};
[Fact]
public void VolumeIteratorGetsCurrent()
{
var sut = new Iterator<Volume>(_volumes);
Assert.Equal("vol1",sut.Current.Name);
}
[Fact]
public void VolumeIteratorGetsNext()
{
var sut = new Iterator<Volume>(_volumes);
sut.MoveNext();
Assert.Equal("vol2",sut.Current.Name);
}
[Fact]
public void VolumeIteratorGetsNextThenSetsCurrent()
{
var sut = new Iterator<Volume>(_volumes);
sut.MoveNext();
sut.Current = new Volume("vol2modified",false);
Assert.Equal("vol2modified",sut.Current.Name);
}
[Fact]
public void VolumeIteratorGetsNextThenSetsCurrentByProperty()
{
var sut = new Iterator<Volume>(_volumes);
sut.MoveNext();
sut.Current.Name = "vol2modifiedAgain";
Assert.Equal("vol2modifiedAgain",sut.Current.Name);
}
[Fact]
public void VolumeIteratorGetsLast()
{
var sut = new Iterator<Volume>(_volumes);
Assert.Equal("vol2",sut.Last.Name);
}
[Fact]
public void VolumeIteratorSetsLast()
{
var sut = new Iterator<Volume>(_volumes);
sut.Last = new Volume("last",true);
Assert.Equal("last",sut.Last.Name);
}
[Fact]
public void VolumeIteratorGetsFirst()
{
var sut = new Iterator<Volume>(_volumes);
Assert.Equal("vol1",sut.First.Name);
}
[Fact]
public void VolumeIteratorSetsFirst()
{
var sut = new Iterator<Volume>(_volumes);
sut.First = new Volume("first",true);
Assert.Equal("first",sut.First.Name);
}
[Fact]
public void MoveNextReturnsTrueIfNotLastItem()
{
var sut = new Iterator<Volume>(_volumes);
Assert.True(sut.MoveNext());
}
[Fact]
public void MoveNextReturnsFalseIfLastItem()
{
var sut = new Iterator<Volume>(_volumes);
sut.MoveNext();
Assert.False(sut.MoveNext());
}
}
}