Question

我正在尝试使用lambda表达式创建KeyValue对集合。

这是我的班级，下面是我的lambda代码。我没能创建KeyValuePair。

我想获得一个Id的KeyValuePair集合，IsReleased for 喜剧电影。我将这些KeyValuePair放在HashSet中进行快速搜索。

 public class Movie{
  public string Name{get;set;}
  public int Id{get;set;}
  public bool IsReleased{get;set;}
  //etc
 }

List<Movie> movieCollection=//getting from BL

var movieIdReleased= new 
HashSet<KeyValuePair<int,bool>>(movieCollection.Where(mov=> mov.Type== "comedy")
                                    .Select(new KeyValuePair<int,bool>(????));

Answer 1

你应该将lambda传递给.Select方法，而不仅仅是表达式：

.Select(movie => new KeyValuePair<int,bool>(movie.Id, movie.IsReleased))

希望有所帮助！

Answer 2

 //.Select(new KeyValuePair<int,bool>(????));
 .Select(movie => new KeyValuePair<int,bool>() 
              { Key = movie.Id, Value = movie.IsReleased} );

Answer 3

var comedyMovies = movieCollection
    .Where(mc => "comedy".Equals(mc.Type, StringComparison.OrdinalIgnoreCase))
    .Select(mc => new KeyValuePair<int, bool>(mc.Id, mc.IsReleased));
var distinctComedyMovies = new HashSet<KeyValuePair<int,bool>>(comedyMovies);

Lambda表达式中的KeyValuePair

3 个答案: