Division by ZERO

[Thomas Markl]

When I divide 10 / 0 then Exception „Divided by zero“ should appear as in example 1.
Why doesn’t it apper in Example 2 with „double d“?
And why POSITIVE Infinity?

class Positive_infinity_test {
public final static void main(String[] args){
//         double d = 10.0 / -0;
         int d = 10 / -0;
         System.out.println("10.0 / -0) = " +d);
          if(d == Double.POSITIVE_INFINITY)
           System.out.println("Positive infinity"+d);
           else
           System.out.println("Negative infinity"+d);
         }
}

C:\Java\EigeneJavaProgramme>java Positive_infinity_test
java.lang.ArithmeticException: / by zero
at Positive_infinity_test.main(Positive_infinity_test.java:5)
Exception in thread "main"

class Positive_infinity_test {
public final static void main(String[] args){
         double d = 10.0 / -0;
//         int d = 10 / -0;
         System.out.println("10.0 / -0) = " +d);
          if(d == Double.POSITIVE_INFINITY)
           System.out.println("Positive infinity"+d);
           else
           System.out.println("Negative infinity"+d);
         }
}

C:\Java\EigeneJavaProgramme>java Positive_infinity_test
10.0 / -0) = Infinity
Positive infinityInfinity

class Positive_infinity_test {
public final static void main(String[] args){
           double d = 10.0 / 0;
//         double d = 10.0 / -0;
//         int d = 10 / -0;
         System.out.println("10.0 / -0) = " +d);
          if(d == Double.POSITIVE_INFINITY)
           System.out.println("Positive infinity"+d);
           else
           System.out.println("Negative infinity"+d);
         }
}

C:\Java\EigeneJavaProgramme>java Positive_infinity_test
10.0 / -0) = Infinity
Positive infinityInfinity

[Bosun Bello]

Check the API. float or double division by zero does not throw NFE.

[Dave Vick]

Thomas
From the JLS section 4.2.4
Floating-point operators produce no exceptions .

[Ilja Preuss]

Originally posted by Thomas Markl:
When I divide 10 / 0 then Exception „Divided by zero“ should appear as in example 1.
Why doesn’t it apper in Example 2 with „double d“?
And why POSITIVE Infinity?

Because it is usefull for the following reason:
lim (x -> +0) (10/x) = positive infinity
That is, the nearer x gets to zero, the bigger gets 10/x

[Dirk Schreckmann]

Take a look at the Incomperable NaN item of Roedy Green's list of Java Gotchas.