Java: Compare Double 0 with Min/Max

Question

I try to compare Doubles Min/Max with 0.0.

Double min = Double.MIN_VALUE;
Double max = Double.MAX_VALUE;

Double d = new Double (0.0);

System.out.println (min < d);
System.out.println (min.compareTo (d) < 0);

System.out.println (d < max);
System.out.println (d.compareTo (max) < 0);

I would expect all output to be true.

But instead I get

false
false
true
true

Why?

Of course, `Double.MIN_VALUE` is 0 so `min < d` would return false because `min = d` . — preciousbetine, Oct 23 '19 at 09:05
Possible duplicate of [Why is Double.MIN\_VALUE in not negative](https://stackoverflow.com/questions/3884793/why-is-double-min-value-in-not-negative) — xenteros, Oct 23 '19 at 09:07
@Jesper, well approximately it is with a little bit of rounding error.. — preciousbetine, Oct 23 '19 at 09:09
Possible duplicate of [Is Double.MIN\_VALUE is greater than zero in Java?](https://stackoverflow.com/questions/5709073/is-double-min-value-is-greater-than-zero-in-java) — Oleksandr Pyrohov, Oct 23 '19 at 09:41

score 6 · Accepted Answer · answered Oct 23 '19 at 09:08

6

Look at the documentation of Double.MIN_VALUE, which says:

A constant holding the smallest positive nonzero value of type double, 2^-1074.

So this is a value larger than 0, which is why you 'false' if you check if it's smaller than zero.

answered Oct 23 '19 at 09:08

Jesper

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xenteros · Answer 2 · 2019-10-23T09:14:44.983

1

The issue is related to IEEE-754. In fact, Double.MIN_VALUE is equal to machine-epsilon which is the number represented by 0.00000...00. The smallest double possible should be referred as

-Double.MAX_VALUE.

edited Oct 23 '19 at 09:14

answered Oct 23 '19 at 09:09

xenteros

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Java: Compare Double 0 with Min/Max

2 Answers2