我已经编写了排序方法的代码测试速度。它生成一个集合并使用不同的方法对其进行排序。
public void TestMethod1()
{
var unsortedCollection = GenerateCollection();
var toSort = unsortedCollection.ToList();
Console.WriteLine("OrderBy x.A: " + Measure(() => toSort.OrderBy(x => x.A).ToArray()) + "ms");
toSort = unsortedCollection.ToList();
Console.WriteLine("OrderBy x: " + Measure(() => toSort.OrderBy(x => x).ToArray()) + "ms");
toSort = unsortedCollection.ToList();
Console.WriteLine("OrderBy x using Comparer: " + Measure(() => toSort.OrderBy(x => x, new Comparer()).ToArray()) + "ms");
toSort = unsortedCollection.ToList();
Console.WriteLine("OrderBy x using Comparer<int>.Default: " + Measure(() => toSort.OrderBy(x => x.A, Comparer<int>.Default).ToArray()) + "ms");
toSort = unsortedCollection.ToList();
Console.WriteLine("OrderBy x using Comparer<SimpleObject>.Default: " + Measure(() => toSort.OrderBy(x => x, Comparer<SimpleObject>.Default).ToArray()) + "ms");
toSort = unsortedCollection.ToList();
Console.WriteLine("Sort: " + Measure(() =>
{
toSort.Sort();
toSort.ToArray();
}) + "ms");
toSort = unsortedCollection.ToList();
Console.WriteLine("Sort using Comparison: " + Measure(() =>
{
toSort.Sort((x, y) => x.A.CompareTo(y.A));
toSort.ToArray();
}) + "ms");
toSort = unsortedCollection.ToList();
Console.WriteLine("Sort using Comparer: " + Measure(() =>
{
toSort.Sort(new Comparer());
toSort.ToArray();
}) + "ms");
}
private List<SimpleObject> GenerateCollection()
{
int length = 10000000;
var list = new List<SimpleObject>();
for (int i=0; i<length; i++)
{
list.Add(new SimpleObject());
}
return list;
}
private long Measure(Action method)
{
Stopwatch sw = new Stopwatch();
sw.Reset();
sw.Start();
method();
sw.Stop();
return sw.ElapsedMilliseconds;
}
public class Comparer: IComparer<SimpleObject>
{
public int Compare(SimpleObject x, SimpleObject y)
{
return x.A.CompareTo(y.A);
}
}
public class SimpleObject: IComparable<SimpleObject>
{
public int A;
private static Random rand = new Random();
private const int maxValue = 1000000;
public SimpleObject()
{
A = rand.Next(maxValue);
}
public int CompareTo(SimpleObject other)
{
return A.CompareTo(other.A);
}
}
以下是结果：
OrderBy x.A: 8732ms
OrderBy x: 19136ms
OrderBy x using Comparer: 17054ms
OrderBy x using Comparer<int>.Default: 8758ms
OrderBy x using Comparer<SimpleObject>.Default: 19817ms
Sort: 8000ms
Sort using Comparison: 9515ms
Sort using Comparer: 8990ms
我想知道为什么 OrderBy 使用 Comparer 的工作时间比没有 Comparer 的时间长，为什么使用比较的 Sort 工作时间比使用 Comparer 的时间长。