If statement that ensures round number

Question

Can I make an if statement in Java like the one below, that ensures that a number is round?

if(some number int)

Answer 1

Yes

System.out.println(6.0 % 1 == 0);

prints

true

while

System.out.println(6.1 % 1 == 0);

prints

false

As the JLS specifies for the remainder operation for floating point numbers :

In the remaining cases, where neither an infinity, nor a zero, nor NaN is involved, the floating-point remainder r from the division of a dividend n by a divisor d is defined by the mathematical relation r = n - (d · q) where q is an integer that is negative only if n/d is negative and positive only if n/d is positive, and whose magnitude is as large as possible without exceeding the magnitude of the true mathematical quotient of n and d.

Therefore, if n is the number you wish to test and d is 1, the remainder r is r = n - q for some integer q. Therefore, if the remainder r is 0, n = q for some integer q, so your tested number n is an integer.

Answer 2

I guess you want to check if a number is an int:

public boolean isObjectInteger(Object o) { return o instanceof Integer; }

Should do the job.

Answer 3

Alternatively, using Math.rint:

if(x == Math.rint(x))