如何在Java中使用泛型和语言运算符以及扩展Number的泛型类 [英] how to use generics in Java with language operators and generic class extending Number

问题描述

我想对两个扩展Number的相同类型的两个泛型参数执行操作。

可能吗？
我总是用泛型参数调用方法，但似乎使用运算符时出现了一些问题（运算符+未定义参数类型T，T）。

  public static< T extends Number> T sum（T a，T b）{
 return a + b; 
} 
  

我做错了什么？

编辑：
我尝试改进一点我的问题。我明白运营商没有为Number类型定义。这件事有点令人难过，因为如果没有像@Victor Sorokin所建议的那样引入新界面，那么执行这样的操作会很好。

但我还是不明白一件事：如果运营商没有在类中实现Number，那么至少在Double类中应该实现，因为我可以使用+运算符双倍。
这两行代码都不会被编译：

  public static< T extends Double> T sum（T a，T b）{
 
 T c = a + b; 
} 
  

为什么？

解决方案

这是不可能的，因为 Number 没有与它关联的+运算符。特别是，你不能这样做：

  Number a = new Integer（1）; 
数字b =新的整数（2）; 
数字c = a + b; 
  

I would like to perform an operation on two generics argument of the same type both extending Number.

Is it Possible? I always used to call methods on generic arguments, but seems there is some problem using operators (The operator + is undefined for the argument type(s) T, T).

public static <T extends Number> T sum(T a, T b){
    return a+ b;
}

What am I doing wrong?

EDIT: I try to improve a little bit my question. I understood that operators are not defined for type Number. It's a bit sad this thing because it would be nice to perform such an operation without introducing new interfaces like suggested by @Victor Sorokin.

But I still don't understand one thing: if operators are not implemented in the class Number, then at least in Double class should be implemented because I can use + operator with double. Neither these line of code will compile:

public static <T extends Double> T sum(T a, T b){

    T c = a +b;
}

why?

解决方案

It's not possible because Number doesn't have a + operator associated with it. In particular, you can't do this:

Number a = new Integer(1);
Number b = new Integer(2);
Number c = a + b;

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