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

A new method has been added with Java 8 to do just that.

import static java.lang.Math.toIntExact;

long foo = 10L;
int bar = toIntExact(foo);

Will throw an ArithmeticException in case of overflow.

See: Math.toIntExact(long)

Several other overflow safe methods have been added to Java 8. They end with exact.

Examples:

• Math.incrementExact(long)
• Math.subtractExact(long, long)
• Math.decrementExact(long)
• Math.negateExact(long),
• Math.subtractExact(int, int)