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List Class
Posted on 2012-12-20
Hi,
I have implemented a class that is a list:
Public class CompareItems
{
Public string type {get; set; }
Public int item1 { get; set; }
Public int item2 { get; set; }
}
Public List< CompareItems> compareJobList = new List< CompareItems>();
I can populate this okay, but I now have a requirement to check that the list does not accept duplicate values. I know this could be done on normal list by using the contains function.
However can it be done on this type of a list?
So I would need to check all 3 values don't exist?
I have implemented a class that is a list:
Public class CompareItems
{
Public string type {get; set; }
Public int item1 { get; set; }
Public int item2 { get; set; }
}
Public List< CompareItems> compareJobList = new List< CompareItems>();
I can populate this okay, but I now have a requirement to check that the list does not accept duplicate values. I know this could be done on normal list by using the contains function.
However can it be done on this type of a list?
So I would need to check all 3 values don't exist?
[X]
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5 Comments
If you're using .NET 3.5 or later, LINQ is the answer to this one:
compareJobList .Where(t => t.item1 == 3);
compareJobList .Where(t => t.item1 == 3);
if less .net 3.5
compareJobList .Exists(t => t.item1 == 3&& t.item2=1)
or
compareJobList .FindAll(t => t.item1 == 3&& t.item2=1)
compareJobList .Exists(t => t.item1 == 3&& t.item2=1)
or
compareJobList .FindAll(t => t.item1 == 3&& t.item2=1)
Active today
If you're using .NET 3.5 or later, LINQ is the answer to this one:I'd suggest Any instead of Where.
compareJobList .Where(t => t.item1 == 3);
using System.Linq;
...
bool exists = compareJobList .Any(t => t.item1 == 3);
Instead of a List<> you can use a HashSet<> (http://msdn.microsoft.com/en-us/library/bb359438.aspx)
A hashset will never store a duplicate
A hashset will never store a duplicate
To be able to check if an item is in a collection, you need to be able to compare them. The default comparison for objects only compares the references, so if you have two objects with the exact same values, they will still not be equal.
Implement the IEquatable<T> interface for the class:
Now you can check if an item exists in the list. In this example, only the first item will be added to the list:
Implement the IEquatable<T> interface for the class:
public class CompareItems : IEquatable<CompareItems> {
public string type { get; set; }
public int item1 { get; set; }
public int item2 { get; set; }
public bool Equals(CompareItems other) {
return type == other.type && item1 == other.item1 && item2 == other.item2;
}
}
Now you can check if an item exists in the list. In this example, only the first item will be added to the list:
CompareItems item1 = new CompareItems { type = "test", item1 = 42, item2 = 1337 };
if (!compareJobList.Contains(item1)) {
compareJobList.Add(item1);
}
CompareItems item2 = new CompareItems { type = "test", item1 = 42, item2 = 1337 };
if (!compareJobList.Contains(item2)) {
compareJobList.Add(item2);
}
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