How to use the unsigned Integer in Java 8 and Java 9?

Question

In the Oracle "Primitive data types" page, it mentions that Java 8 adds support for unsigned ints and longs:

int: By default, the int data type is a 32-bit signed two's complement integer, which has a minimum value of −2³¹ and a maximum value of 2³¹−1. In Java SE 8 and later, you can use the int data type to represent an unsigned 32-bit integer, which has a minimum value of 0 and a maximum value of 2³²−1. Use the Integer class to use int data type as an unsigned integer. See the section The Number Classes for more information. Static methods like compareUnsigned, divideUnsigned etc have been added to the Integer class to support the arithmetic operations for unsigned integers.

long: The long data type is a 64-bit two's complement integer. The signed long has a minimum value of −2⁶³ and a maximum value of 2⁶³−1. In Java SE 8 and later, you can use the long data type to represent an unsigned 64-bit long, which has a minimum value of 0 and a maximum value of 2⁶⁴−1. Use this data type when you need a range of values wider than those provided by int. The Long class also contains methods like compareUnsigned, divideUnsigned etc to support arithmetic operations for unsigned long.

However, I find no way to declare an unsigned long or integer. The following code, for example, gives a compiler error message of "the literal is out of range" (I'm using Java 8, of course), when it should be in range (the value assigned is precisely 2⁶⁴−1):

public class Foo {     static long values = 18446744073709551615L;          public static void main(String[] args){         System.out.println(values);     }   } 

So, is there any way to declare an unsigned int or long?

Answer 1

Well, even in Java 8, long and int are still signed, only some methods treat them as if they were unsigned. If you want to write unsigned long literal like that, you can do

static long values = Long.parseUnsignedLong("18446744073709551615");  public static void main(String[] args) {     System.out.println(values); // -1     System.out.println(Long.toUnsignedString(values)); // 18446744073709551615 } 

Answer 2

Per the documentation you posted, and this blog post - there's no difference when declaring the primitive between an unsigned int/long and a signed one. The "new support" is the addition of the static methods in the Integer and Long classes, e.g. Integer.divideUnsigned. If you're not using those methods, your "unsigned" long above 2^63-1 is just a plain old long with a negative value.

From a quick skim, it doesn't look like there's a way to declare integer constants in the range outside of +/- 2^31-1, or +/- 2^63-1 for longs. You would have to manually compute the negative value corresponding to your out-of-range positive value.