CODEWITHSUNDEEP
javamathnanarithmetic-expressions
Pranit Bankar
Pranit Bankar

Reputation: 473

How to display NaN in Java?

In Java, I am dividing by zero, which obviously does not produce a number. 

public class tempmain {
    public static void main(String args[])
    {
        float a=3/0;
        System.out.println(a);
    }
}

I expect the output to be "NaN", but it shows the following error:

Exception in thread "main" java.lang.ArithmeticException: / by zero
    at tempmain.main(tempmain.java:6)

Is there any way (apart from if(denominator==0)) by which NaN can be displayed?

Upvotes: 0

Views: 1289

Answers (3)

J Richard Snape
J Richard Snape

Reputation: 20344

You are getting the unexpected ArithmeticException because of the way that your numeric literals 3 and 0 are treated. They are interpreted as integers, despite the fact that you assign a to be a float. Java will interpret 3 as an integer, 3f as a float and 3.0 or 3d as a double. The division is performed as integer division and the result cast to a float. To see another interesting other effect of this - try float a = 1/3 and inspect a - you will find it is 0.0, rather than 0.3333.... as you might expect.

To get rid of the Exception - change

float a = 3/0;

for 

float a = 3f/0;

As others have noted in comments and answers, if you then print a, you will see Infinity rather than NaN. If you really want to print NaN in this case, you can test a for being infinite i.e. 

if (Float.isInfinite(a)) {
     System.out.println("I want to print Infinity as NaN");
}

but I'd recommend against it as highly misleading - but I suspect that's not what you meant anyway

Upvotes: 7

HappyCactus
HappyCactus

Reputation: 2014

What about:

public class tempmain {

public static void main(String args[])
{
    try {
       float a=3/0;
       System.out.println(a);
    } catch (ArithmeticException x) {
       System.out.println("Not Evaluable");
    }
}

}

There is also this option:

{
...
//if (a != a) {        // these two are equivalent
if (Float.isNaN(a)) {
  System.out.println("NaN");
  }
}

See: Float.NaN == Float.NaN

Upvotes: 2

Vladimir Matveev
Vladimir Matveev

Reputation: 127751

First, dividing by zero in floating point numbers does not give NaN, it gives infinity. Second, you're dividing integers, not floats.

float a = 3.0f/0.0f;
System.out.println(a);  // Prints Infinity

Upvotes: 4

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