C＃中未显示Int []值列表的字典

Question

I am trying to display the values from a dictionary function but it does not display the value, what it shows is below -

1007 System.Collections.Generic.List`1[System.Int32[]] 

1006 System.Collections.Generic.List`1[System.Int32[]] 

1009 System.Collections.Generic.List`1[System.Int32[]] 

1008 System.Collections.Generic.List`1[System.Int32[]]

the code I am using is shown below

    clsCollaborativeFilter mri = new clsCollaborativeFilter();
    Dictionary<int, List<int[]>> movRecommendations = mri.aList1();

    foreach (KeyValuePair<int, List<int[]>> kvp in movRecommendations)
    {
        da.Text += kvp.Key;
        da.Text += " ";
        da.Text += kvp.Value;
        da.Text += "<br/>";
    }
    return da.Text;

I cant seem to understand why this is happening

Answer 1

you are adding a List of an Array of ints to a string, in the line: da.Text += kvp.Value; so what it is doing, is it is adding the signature of the List of Array s because it doesn't know exactly what you are trying to do.

What you can do instead is:

da.Text += String.Join(", ", kvp.Value.SelectMany(i => i));

Answer 2

...or assuming that it really is a dictionary-of-list-of-int-arrays, then:

StringBuilder sb = new StringBuilder();
foreach(Int32 key in movRecommendations.Key) {
    List<Int32[]> listOfArrays = movRecommendations[ key ];

    sb.Append( key );
    sb.AppendLine();
    foreach(Int32[] array in listOfArrays) {
        Boolean isFirst = true;
        foreach(Int32 val in array) {
            if( !isFirst ) sb.Append( ", " );
            sb.Append( val );
            isFirst = false;
        }
        sb.AppendLine();
    }
    sb.AppendLine("<br />");
}
da.Text = sb.ToString();

Answer 3

I think what you actually want is this:

Dictionary< int, List<int> >

...a List<int[]> doesn't make much sense to me.

Answer 4

clsCollaborativeFilter mri = new clsCollaborativeFilter();
Dictionary<int, List<int[]>> movRecommendations = mri.aList1();

foreach (KeyValuePair<int, List<int[]>> kvp in movRecommendations)
{
    da.Text += kvp.Key;
    da.Text += " ";
    da.Text += string.Join(",",kvp.Value);
    da.Text += "<br/>";
}
return da.Text;

Answer 5

Dictionary<int, List<int[]>> movRecommendations = new Dictionary<int, List<int[]>>(){
    {0, new List<int[]>(){ new int[]{1, 2, 3} }},
    {1, new List<int[]>(){ new int[]{7, 8, 9} }}
};
string da = String.Empty; 
foreach (KeyValuePair<int, List<int[]>> kvp in movRecommendations)
{
    da += kvp.Key;
    da += " ";
    da += String.Join(", ", kvp.Value.SelectMany(i => i));
    da += "<br/>";
}
Console.WriteLine (da);

This will write out 0 1, 2, 3<br/>1 7, 8, 9<br/>