Is it possible to check the type of an argument passed to a function and treat it accordingly in JAVA?

Question

For example, there needs to be a written a generic program for addition. It needs to be intelligent in a way that it determines the type of arguments passed to it and then output the answer in the same type. For more elaboration:

If I want to write only one method to add two numbers ( of any type like int, float, double etc), what should I do that the method itself determines the type of number passed and returns the calculated sum in the same type?

Is there any way to sort this out? Any help would be highly appreciated!

Code view: For example arguments passed are 5 & 6 i.e. integers.

addition(5,6);

Now, what I want is a function add that somehow determines the type (i.e. integer in this case) & returns the result. Like:

public (determined return type) add((determined returned type) space variable, (determined returned type) space variable){ return result; }

score 0 · Answer 1 · answered Mar 07 '15 at 13:09

0

This should work:

public static <T extends Number> T addition(T a, T b) {
    if (a instanceof Integer)
        return (T) (Object) (a.intValue() + b.intValue());

    // + similar code for all primitive types and possibly also BigInteger and BigDecimal
}

answered Mar 07 '15 at 13:09

Crazyjavahacking

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What is T in this case? – Siddique Hassan Mar 07 '15 at 13:11
Generic type parameter that is determined at runtime. – Crazyjavahacking Mar 07 '15 at 13:13
What should be the return type of function that calls a generic method? In this case = "add(a,b)" – Siddique Hassan Mar 08 '15 at 06:59
The return type is T, the same type as the type of parameters. – Crazyjavahacking Mar 08 '15 at 07:31
oops. I asked in a wrong way! i meant: I called it from another class with the help of class' object. when the generic method returns the result it has to be stored in some variable... Of what type it should be? Like we use : int result = add(5,6); With what "int" should be replaced in case of unknown type output? – Siddique Hassan Mar 08 '15 at 07:49

score 0 · Answer 2 · answered Mar 07 '15 at 13:10

0

You could have a method declared:

public <N extends Number> N add(N n1, N n2)

This would require instanceof checks to actually implement and return the desired type.

answered Mar 07 '15 at 13:10

Brett Okken

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score 0 · Answer 3 · answered Mar 07 '15 at 13:32

Is it possible to check the type of an argument passed to a function and treat it accordingly in JAVA?

3 Answers3