Java How To Add Two Numbers

Java How To Add Two Numbers

How to add two java.lang.Numbers?

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Asked 11 years, 7 months ago

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I have two Numbers. Eg:

Number a = 2;
Number b = 3;
//Following is an error:
Number c = a + b;

Why arithmetic operations are not supported on Numbers? Anyway how would I add these two numbers in java? (Of course I'm getting them from somewhere and I don't know if they are Integer or float etc).


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edited Dec 8 '11 at 10:34


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asked Apr 27 '10 at 13:05


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  • 1

    Are they actually assigned like that? I mean, is Number a = primitiveNumber valid? If you are getting them from some Method which returns "something extends Number" you could actually check whether the returned Number is an instanceof Double or Float or BigDecimal or whatever. 

    – Tedil

     Apr 27 '10 at 14:20
  • 1

    @Tedil Yes an assignment of this kind is possible since Java 1.5, thanks to a feature know as "autoboxing". The primitive number 2 is an int, which is boxed to an Integer, which is a subclass of Number

    – Christian Semrau

     Apr 27 '10 at 14:23

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10 Answers




You say you don't know if your numbers are integer or float... when you use the Number class, the compiler also doesn't know if your numbers are integers, floats or some other thing. As a result, the basic math operators like + and - don't work; the computer wouldn't know how to handle the values.