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How to implement infinity in Java?


Question

Does Java have anything to represent infinity for every numerical data type? How is it implemented such that I can do mathematical operations with it?

E.g.

int myInf = infinity; //However it is done
myInf + 5; //returns infinity
myInf*(-1); //returns negative infinity

I have tried using very large numbers, but I want a proper, easy solution.

2016/04/16
1
143
4/16/2016 7:06:19 PM

Accepted Answer

double supports Infinity

double inf = Double.POSITIVE_INFINITY;
System.out.println(inf + 5);
System.out.println(inf - inf); // same as Double.NaN
System.out.println(inf * -1); // same as Double.NEGATIVE_INFINITY

prints

Infinity
NaN
-Infinity

note: Infinity - Infinity is Not A Number.

2012/10/18
195
10/18/2012 10:04:20 AM

I'm supposing you're using integer math for a reason. If so, you can get a result that's functionally nearly the same as POSITIVE_INFINITY by using the MAX_VALUE field of the Integer class:

Integer myInf = Integer.MAX_VALUE;

(And for NEGATIVE_INFINITY you could use MIN_VALUE.) There will of course be some functional differences, e.g., when comparing myInf to a value that happens to be MAX_VALUE: clearly this number isn't less than myInf.

There's also a library that actually has fields POSITIVE_INFINITY and NEGATIVE_INFINITY, but they are really just new names for MAX_VALUE and MIN_VALUE.

2013/07/31

To use Infinity, you can use Double which supports Infinity: -

    System.out.println(Double.POSITIVE_INFINITY);
    System.out.println(Double.POSITIVE_INFINITY * -1);
    System.out.println(Double.NEGATIVE_INFINITY);

    System.out.println(Double.POSITIVE_INFINITY - Double.NEGATIVE_INFINITY);
    System.out.println(Double.POSITIVE_INFINITY - Double.POSITIVE_INFINITY);

OUTPUT: -

Infinity
-Infinity
-Infinity

Infinity 
NaN
2012/10/18

The Double and Float types have the POSITIVE_INFINITY constant.

2012/10/18

I'm not sure that Java has infinity for every numerical type but for some numerical data types the answer is positive:

Float.POSITIVE_INFINITY
Float.NEGATIVE_INFINITY

or

Double.POSITIVE_INFINITY
Double.NEGATIVE_INFINITY

Also you may find useful the following article which represents some mathematical operations involving +/- infinity: Java Floating-Point Number Intricacies.

2012/10/18

Only Double and Float type support POSITIVE_INFINITY constant.

2012/10/18