我可以像在 C# 中一样在 Java 中通过泛型类型重载类吗？

Question

public class A<T>
{
    // do something
}
public class A<T, B>
{
    // do something
}

I just want to create a class that just contains value of every generic type. Like Tuple in C#:

Tuple<int> intContainer = new Tuple<int>(5);
Tuple<int, int> twoIntContainer = new Tuple<int, int>(5, 5);
Tuple<int, int, int> threeIntContainer = new Tuple<int, int, int>(5, 5, 5);

Answer 1

First things first, you can not have primitive types as generic parameters, only reference types. Thus, you can not have Tuple<int> at all (at least not yet, thats in the works), but need to use Tuple<Integer> .

Furthermore, Java does not allow overloading a class, at all. You can not have two definitions for a class, thus you can not have the same class with a different amount of generic parameters. You can subclass the class, though, and add more generic parameters to the subclass, with all the pros and cons that has.

With Java 14, we got nominal tuples in the form of Records as a preview feature ( 2nd preview in Java 15 ). Thus, creating ad-hoc data structures that can hold the required elements has become much easier, greatly reducing the demand for general-purpose tuple types.

Related reading:

• Data Classes and Sealed Types for Java