C# 比较两个列表-如果一个列表中的任何对象属性已更改或列表中添加了新对象,请返回该对象
假设我有一门课:C# 比较两个列表-如果一个列表中的任何对象属性已更改或列表中添加了新对象,请返回该对象,c#,linq,list,compare,C#,Linq,List,Compare,假设我有一门课: public class Product { public string Id { get; set; } public int Quantity { get; set; } } 然后我有两个列表: var oldList = new List<Product>(){ new Product(){ Id = "1", Quantity = 1 } }; var newList =
public class Product
{
public string Id { get; set; }
public int Quantity { get; set; }
}
然后我有两个列表:
var oldList = new List<Product>(){
new Product(){
Id = "1", Quantity = 1
}
};
var newList = new List<Product>(){
new Product(){
Id = "1", Quantity = 5
}
};
如果一个新项目被添加到
新列表中
,那么我想返回该项目(Id为=“2”)的产品对象您可以尝试以下方法:
var oldList = new List<Product>(){
new Product(){
Id = "1", Quantity = 1
}
};
var newList = new List<Product>(){
new Product(){
Id = "1", Quantity = 1
},
new Product(){
Id = "2", Quantity = 1
}
};
var result = newList.Except(oldList);
public List<MyItems> GetItemsFromANotInThatAreNotInB(List<MyItems> A, List<MyItems> B)
{
return (from b in B
where !(from a in A select a.Id).Contains(b.Id)
select b).ToList();
}
但是您必须首先为产品
类实现IEquatable
接口
public class Product : IEquatable<Product>
{
public string Id { get; set; }
public int Quantity { get; set; }
public bool Equals(Product product)
{
if (product == null)
{
return false;
}
return (Id == product.Id) && (Quantity == product.Quantity);
}
}
公共类产品:IEquatable
{
公共字符串Id{get;set;}
公共整数数量{get;set;}
公共布尔等于(产品)
{
如果(产品==null)
{
返回false;
}
退货(Id==product.Id)&(数量==product.Quantity);
}
}
您可以尝试以下方法:
var oldList = new List<Product>(){
new Product(){
Id = "1", Quantity = 1
}
};
var newList = new List<Product>(){
new Product(){
Id = "1", Quantity = 1
},
new Product(){
Id = "2", Quantity = 1
}
};
var result = newList.Except(oldList);
public List<MyItems> GetItemsFromANotInThatAreNotInB(List<MyItems> A, List<MyItems> B)
{
return (from b in B
where !(from a in A select a.Id).Contains(b.Id)
select b).ToList();
}
但是您必须首先为产品
类实现IEquatable
接口
public class Product : IEquatable<Product>
{
public string Id { get; set; }
public int Quantity { get; set; }
public bool Equals(Product product)
{
if (product == null)
{
return false;
}
return (Id == product.Id) && (Quantity == product.Quantity);
}
}
公共类产品:IEquatable
{
公共字符串Id{get;set;}
公共整数数量{get;set;}
公共布尔等于(产品)
{
如果(产品==null)
{
返回false;
}
退货(Id==product.Id)&(数量==product.Quantity);
}
}
首先,您应该实现相等比较器来比较两个产品项是否相等:
class ProductEqualityComparer : IEqualityComparer<Product>
{
public bool Equals(Product x, Product y)
{
if (Object.ReferenceEquals(x, y)) return true;
if (Object.ReferenceEquals(x, null) || Object.ReferenceEquals(y, null))
return false;
return x.Id == y.Id && x.Quantity == y.Quantity;
}
public int GetHashCode(Product product)
{
if (Object.ReferenceEquals(product, null)) return 0;
return product.Id.GetHashCode() ^ product.Quantity.GetHashCode();
}
}
首先,您应该实现相等比较器来比较两个产品项是否相等:
class ProductEqualityComparer : IEqualityComparer<Product>
{
public bool Equals(Product x, Product y)
{
if (Object.ReferenceEquals(x, y)) return true;
if (Object.ReferenceEquals(x, null) || Object.ReferenceEquals(y, null))
return false;
return x.Id == y.Id && x.Quantity == y.Quantity;
}
public int GetHashCode(Product product)
{
if (Object.ReferenceEquals(product, null)) return 0;
return product.Id.GetHashCode() ^ product.Quantity.GetHashCode();
}
}
一种解决方法,因此您不必使用,只需使用Linq来处理以下对象:
var oldList = new List<Product>(){
new Product(){
Id = "1", Quantity = 1
}
};
var newList = new List<Product>(){
new Product(){
Id = "1", Quantity = 1
},
new Product(){
Id = "2", Quantity = 1
}
};
var result = newList.Except(oldList);
public List<MyItems> GetItemsFromANotInThatAreNotInB(List<MyItems> A, List<MyItems> B)
{
return (from b in B
where !(from a in A select a.Id).Contains(b.Id)
select b).ToList();
}
public List GetItemsFromANotInThatAreNotInB(列表A、列表B)
{
返回(从b中的b返回)
其中!(从a中选择a.Id)。包含(b.Id)
选择b).ToList();
}
一种变通方法,因此您不必使用,只需使用Linq来处理以下对象:
var oldList = new List<Product>(){
new Product(){
Id = "1", Quantity = 1
}
};
var newList = new List<Product>(){
new Product(){
Id = "1", Quantity = 1
},
new Product(){
Id = "2", Quantity = 1
}
};
var result = newList.Except(oldList);
public List<MyItems> GetItemsFromANotInThatAreNotInB(List<MyItems> A, List<MyItems> B)
{
return (from b in B
where !(from a in A select a.Id).Contains(b.Id)
select b).ToList();
}
public List GetItemsFromANotInThatAreNotInB(列表A、列表B)
{
返回(从b中的b返回)
其中!(从a中选择a.Id)。包含(b.Id)
选择b).ToList();
}
var diffList=oldList.Where(o=>!newList.Any(n=>n.Id==o.Id)).Union(newList.Where(n=>!oldList.Any(o=>n.Id==o.Id))代码>?var diffList=oldList.Where(o=>!newList.Any(n=>n.Id==o.Id)).Union(newList.Where(n=>!oldList.Any(o=>n.Id==o.Id))代码>?