对同一方法使用不同的数据类型

Question

I want to use double values and int values separately in one method as parameters of the method how can I achieve that? The method is multiplying two integer numbers and two double numbers in the same method. The output should be two lines one for the integer and the other for the double value

Answer 1

The most efficient way would be to overload the method :

void foo(int i)
void foo(double i)

But it is also valid to assign an int to a double , so you could also provide only :

void foo(double i)

to accept both int and double .

An alternative to overloading would be to define a generic class with a method that accepts the generic type :

public class Bar<T extends Number>{
   public void foo(T t){
      ...
   }
}

And you could so instantiate them :

Bar<Integer> barInt = new Bar<>();
barInt .foo(3);
Bar<Double> barDouble = new Bar<>();
barDouble.foo(3);

Note that numeric wrappers consume more memory as primitive counter parts.
So the first way with overloading is really the most efficient.

And you have still many other ways to handle this question. All that to say that you should use a way or another according your requirement.

Answer 2

For some calculation which are typesafe for int/double you can just use this:

<T> T calc(T a, Tb) { };

If you want to use functions for a special Type (rounding/floating behaviour/...) you can use instance of and call a help method with INT or DOUBLE or ... or just do it in if-else .