订购清单<t> </t>

Question

我有一个名为jobList的自定义对象列表。该列表有很多字段，但我想按两个字段排序，FolderID和JobName。该列表如下所示：

job.FolderID = 3
job.JobName = "oper01_quick"

job.FolderID = 3
Job.JobName = "oper02_quick"

job.FolderID = 1
job.JobName = "min01_selfie"

job.FolderID = 2
job.JobName = "max01_experion"

job.FolderID = 2
job.JobName = "max02_experion"

我想对此列表进行排序，使其显示如下：

job.FolderID = 1
job.JobName = "min01_selfie"

job.FolderID = 2
job.JobName = "max01_experion"

job.FolderID = 2
job.JobName = "max02_experion"

job.FolderID = 3
job.JobName = "oper01_quick"

job.FolderID = 3
Job.JobName = "oper02_quick"

我想如果我做了这个LINQ OrderBy，那么：

jobList.OrderBy(j => j.FolderID).ThenBy(j => j.JobName);

它会实现这一目标。但事实并非如此。它使订单看起来像这样：

job.FolderID = 1
job.JobName = "min01_selfie"

job.FolderID = 2
job.JobName = "max01_experion"

job.FolderID = 3
job.JobName = "oper01_quick"

job.FolderID = 2
job.JobName = "max02_experion"

job.FolderID = 3
Job.JobName = "oper02_quick"

任何人都可以帮我订购正确的清单吗？

谢谢，

Chewdoggie

Answer 1

你在如何进行排序方面是正确的，但是你需要将它分配给变量以获得生成的排序集合：

请参阅.NET小提琴：http://dotnetfiddle.net/wISQVv

这基本上就是它的作用：

var sortedJobs = jobs.OrderBy(j => j.FolderID).ThenBy(j => j.JobName);

foreach(var job in sortedJobs){
    Console.WriteLine(job.FolderID + " " + job.JobName);
}

Answer 2

我只能看到一种可能的扩展：您没有将OrderBy / ThenBy结果分配回源变量。

这些方法（以及整个LINQ）不会更改源集合。而不是那样，他们创建了具有排序元素的新集合。这就是你必须分配回来的原因：

jobList = jobList.OrderBy(j => j.FolderID).ThenBy(j => j.JobName).ToList();

要对列表进行排序，您必须使用Sort方法，使用自定义比较器：

public class JobComparer : IComparer<Job>
{
    public int Compare(Job x, Job y)
    {
        var folderDifference = x.FolderId.CompareTo(y.FolderId);
        return folderDifference == 0 ? x.JobName.CompareTo(y.JobName) : folderDifference;
    }
}

jobList.Sort(new JobComparer());

Answer 3

jobs.OrderBy(j => j.JobName).OrderBy(j => j.FolderId)

似乎工作正常。

Answer 4

如果您的Job课程如下：

public class Job
{
    public int FolderId { get; set; }

    public string JobName { get; set; }
}

然后实施IComparer<T>：

public class JobComparer : IComparer<Job>
{
    public int Compare(Job x, Job y)
    {
        if (x.FolderId != y.FolderId) return x.FolderId.CompareTo(y.FolderId);

        return x.JobName.CompareTo(y.JobName);
    }
}

并使用它：

var orderedList = items.OrderBy(x => x, new JobComparer()).ToList();

这应该给出您期望的结果。这是LINQPad中的输出：