In Java:
long: The long data type is a 64-bit two’s complement integer. The signed long has a minimum value of -2^63 and a maximum value of 2^63-1. 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 2^64-1. 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.
In Dart:
int
Integer values no larger than 64 bits, depending on the platform. On the Dart VM, values can be from -2^63 to 2^63 – 1. Dart that’s compiled to JavaScript uses JavaScript numbers, allowing values from -2^53 to 2^53 – 1.
So, you can exactly use int in Dart for the equivalent of long in Java. But beware of the caveat when compiled to JavaScript.