如何对用户创建的列表进行排序<;用户类>;C#中的集合
本文关键字:用户 lt 集合 gt 创建 列表 排序 | 更新日期: 2023-09-27 18:03:33
我希望对集合List<UserClass>
进行排序
基于用户定义的该UserClass中的各种属性中的一个属性。
有效吗
List<Function> objFunctionsList = new List<Function>();
// populating data in objFunctionsList
objFunctionsList = objFunctionsList.OrderBy(x => x.Name).ToList();
只需使用linq扩展方法orderby
var sorted=list.OrderBy(x=>x.MyProperty);
如果您需要一个列表作为结果,那么添加ToList()
,例如
var sortedList=list.OrderBy(x=>x.MyProperty).ToList();
或者你可以使用这个扩展类
public static class SortExtension {
public static Comparison<T> GetComparer<T, TP>(Expression<Func<T, IComparable<TP>>> propertyExpression) {
if (propertyExpression == null) throw new ArgumentNullException();
var member = ((propertyExpression.Body is UnaryExpression) ? ((UnaryExpression)propertyExpression.Body).Operand : propertyExpression.Body) as MemberExpression;
if (member == null) throw new ArgumentException();
var parameterA = Expression.Parameter(typeof(T), "a");
var parameterB = Expression.Parameter(typeof(T), "b");
var nullExpr = Expression.Constant(null);
var valueA = Expression.Property(parameterA, member.Member.Name);
var valueB = Expression.Property(parameterB, member.Member.Name);
var compare = Expression.Call(valueA, typeof(TP).GetMethod("CompareTo", new[] { typeof(TP) }), valueB);
var checkBPropNull = Expression.Condition(Expression.Equal(valueB, nullExpr), Expression.Constant(0), Expression.Constant(-1));
var checkAPropertyNull = Expression.Condition(Expression.Equal(valueA, nullExpr), checkBPropNull, compare);
var checkBNullANot = Expression.Condition(Expression.Equal(parameterB, nullExpr), Expression.Constant(1), checkAPropertyNull);
var checkBNullANull = Expression.Condition(Expression.Equal(parameterB, nullExpr), Expression.Constant(0), Expression.Constant(-1));
var checkANull = Expression.Condition(Expression.Equal(parameterA, nullExpr), checkBNullANull, checkBNullANot);
return (a, b) => Expression.Lambda<Func<T, T, int>>(checkANull, parameterA, parameterB).Compile()(a, b);
}
public static void SortBy<T, TP>(this List<T> source, Expression<Func<T, IComparable<TP>>> propertyExpression) {
if (source == null) throw new ArgumentNullException();
source.Sort(GetComparer(propertyExpression));
}
}
然后你就可以做了
列表。SortBy(x=>x.MyProperty(;
Expression构建生成一个功能等同于的比较器
list.Sort((a,b) => {
if (a == null) return (b==null) ? 0 :-1;
if (b==null) return 1;
if (a.MyProperty == null) return (b.MyProperty==null) ? 0 : -1;
return a.T1.CompareTo(b.T1);
});
users.Sort((u1, u2) => {
return u1.Age.CompareTo(u2.Age);
});
例如,这将按Age
进行排序。
如果您的列表是列表,则:
list.Sort((a, b) => {
if (a==null) return (b==null) ? 0 : -1;
if (b==null) return 1;
if (a.Property==null) return (b.Property==null) ? 0 : -1;
return a.Property.CompareTo(b.Property);
});