Was this page helpful?
Your feedback about this content is important. Let us know what you think.
Additional feedback?
1500 characters remaining
new Constraint
Collapse the table of content
Expand the table of content

new Constraint (C# Reference)

The new constraint specifies that any type argument in a generic class declaration must have a public parameterless constructor. To use the new constraint, the type cannot be abstract.

Apply the new constraint to a type parameter when your generic class creates new instances of the type, as shown in the following example:

class ItemFactory<T> where T : new()
    public T GetNewItem()
        return new T();

When you use the new() constraint with other constraints, it must be specified last:

public class ItemFactory2<T>
    where T : IComparable, new()

For more information, see Constraints on Type Parameters (C# Programming Guide).

For more information, see the C# Language Specification.

  • 4.4.3 Satisfying constraints

  • 10.1.6 Type parameter constraints

Community Additions

© 2015 Microsoft