CODEWITHSUNDEEP
javaif-statementdouble
Andre Liberty
Andre Liberty

Reputation: 757

Compare Double.MIN_VALUE and 0

Why this code does't work? Actually,this is just the small part of a big program. It has to compare Double.MIN_VALUE to different values, it works with all values except 0. ,why? Thanks! 

double d = Double.MIN_VALUE;
if (0. > d) {
    System.out.println("OK");
}

Upvotes: 4

Views: 3386

Answers (5)

Thomas Weller
Thomas Weller

Reputation: 59305

Double.MIN_VALUE is actually a bad name for the constant in Java. It does not fit to int.MIN_VALUE. In C# it is called Double.Epsilon, which IMHO fits better.

So, Double.MIN_VALUE is not the largest negative double value that exists. IMHO there's no such constant for the largest discrete Double number. Otherwise, the largest negative number is Double.NEGATIVE_INFINITY.

Upvotes: 3

j_v_wow_d
j_v_wow_d

Reputation: 511

If you are looking to compare a value to the smallest number (the negative value with the greatest magnitude) you might want to look at Double.NEGATIVE_INFINITY which the Java documentation states is:

"A constant holding the negative infinity of type double. It is equal to the value returned by Double.longBitsToDouble(0xfff0000000000000L)."

Upvotes: 0

Estimate
Estimate

Reputation: 1461

The Double.MIN_VALUE is 4.9E-324. And this is not less than 0. But it is not actually 0.

If you print 

System.out.println(4.9E-324d > 0.);//this is true

In this sense,

0.0000000000...0001 != 0. But it tends to 0

The same way 4.9E-324d != 0 but tends to 0

Upvotes: 4

Chand Priyankara
Chand Priyankara

Reputation: 6784

Double.MIN_VALUE is equal to the hexadecimal floating-point literal 0x0.0000000000001P-1022 and also equal to Double.longBitsToDouble(0x1L).

So your condition fails!

Upvotes: 0

SMA
SMA

Reputation: 37023

You are doing decimal number comparison. If you say try something like:

 System.out.println(0.000000000000001d == 0.);//print false

You will get false. If i read java docs it says:

/**
 * A constant holding the smallest positive nonzero value of type
 * {@code double}, 2<sup>-1074</sup>. It is equal to the
 * hexadecimal floating-point literal
 * {@code 0x0.0000000000001P-1022} and also equal to
 * {@code Double.longBitsToDouble(0x1L)}.
 */

So its near to zero but not really 0.

Upvotes: 2

Related Questions