Safely casting long to int in Java?

Question

What's the most idiomatic way in Java to verify that a cast from `long` to `int` does not lose any information? This is my current implementation: public static int safeLongToInt(long l) { int i = (int)l; if ((long)i != l) { throw new IllegalArgumentException(l + " cannot be cast to int without changing its value."); } return i; }

Answer 1

Java 8 and up you can call Math.toIntExact():

import static java.lang.Math.toIntExact;

long longVal = 1L;

int intVal = toIntExact(longVal);

Otherwise you can rewrite your code as follows:

public static int safeLongToInt(long l) {

if (l < Integer.MIN_VALUE || l > Integer.MAX_VALUE) {

throw new IllegalArgumentException

(l + " cannot be cast to int without changing its value.");

}

return (int) l;

}