How use Object while creating Generic class?

Question

I want to create a generic class of Object.

class Calculator<Object> {

         // addition function for addition of two numbers (Integer , Float)

    Object addition(Object first, Object second)
    {
        
        return  ;    //Should return as Object

    }
}

Thanks in Advance... (P.S. NOT going to use it in project......Asking just for my conceptual clarity)

Answer 1

If you want to define a generic class, better use a capital letter as the generic type name, for example

class Calculator<T> {
    T addition(T first, T second) {
        //how to add two generic objects?
    }
}

Maybe you don't want to add two arbitrary objects, but Numbers

class Calculator<T extends Number> {
    T addition(T first, T second) {
        return first + second; //does not compile!
    }
}

The sad news is that Number does not have an add method, and you can't just use the + operator. Maybe you can define an abstract class or interface

interface Calculator<T extends Number> {
    default T addition(@Nullable T first, @Nullable T second) {
        if (first == null || second == null) {
            return first == null ? second : first;
        }
        return nonNullAddition(first, second);
    }
    
    T nonNullAddition(@NotNull T first, @NotNull T second);
}

and implement for the cases you need

class IntCalculator implements Calculator<Integer> {
    @Override
    public Integer nonNullAddition(@NotNull Integer first, @NotNull Integer second) {
        return first + second;
    }
}

class BigDecimalCalculator implements Calculator<BigDecimal> {
    @Override
    public BigDecimal nonNullAddition(@NotNull BigDecimal first, @NotNull BigDecimal second) {
        return first.add(second);
    }
}

Yet, this might be cumbersome. If you don't care about precision, you can cast (more properly it is a widening conversion) everything to double; if you care about precision you can use BigDecimal.

class Calculator {
    public double addition(double first, double second) {
        return first + second;
    }

    public BigDecimal addition(BigDecimal first, BigDecimal second) {
        return first.add(second);
    }
}

and use it in the following way:

double f = 1.0;
int i = 2;
Calculator calc = new Calculator();
double sum = calc.addition(f, i);
BigDecimal preciseSum = calc.addition(new BigDecimal(f), new BigDecimal(i));