How to get the maximum safest integer of a Double in Java

Question

Having in mind that Java's doubles are double-precision floating-point numbers. And the maximum integer without loosing precision is 9007199254740991 or 2⁵³-1

Is there any clean way of getting this value? For instance, like a constant as in JavaScript's MAX_SAFE_INTEGER

Answer 1

There is an internal JDK class named sun.misc.DoubleConsts which has some constants that you could use to generate the value you're looking for using the "accpetable" magic numbers of 1 and 2, but it doesn't have the number defined itself.

public static long MAX_SAFE_VALUE = 
        sun.misc.DoubleConsts.SIGNIF_BIT_MASK * 2 + 1;

// alternatively
public static long MAX_SAFE_VALUE = 
        Math.pow(2, sun.misc.DoubleConsts.SIGNIFICAND_WIDTH) - 1;

However, relying on a class in the sun.misc package is not a very "clean" approach, so I'd just create my own constant.