# How to round up integer division and have int result in Java?

By | July 24, 2019

# Question

I just wrote a tiny method to count the number of pages for cell phone SMS. I didn’t have the option to round up using `Math.ceil`, and honestly it seems to be very ugly.

Here is my code:

``````public class Main {

/**
* @param args the command line arguments
*/
public static void main(String[] args) {
String message = "today we stumbled upon a huge performance leak while optimizing a raycasting algorithm. Much to our surprise, the Math.floor() method took almost half of the calculation time: 3 floor operations took the same amount of time as one trilinear interpolation. Since we could not belive that the floor-method could produce such a enourmous overhead, we wrote a small test program that reproduce";

System.out.printf("COunt is %d ",(int)messagePageCount(message));

}

public static double messagePageCount(String message){
if(message.trim().isEmpty() || message.trim().length() == 0){
return 0;
} else{
if(message.length() <= 160){
return 1;
} else {
return Math.ceil((double)message.length()/153);
}
}
}
``````

I don’t really like this piece of code and I’m looking for a more elegant way of doing this. With this, I’m expecting 3 and not 3.0000000. Any ideas?

# Solution

To round up an integer division you can use

``````import static java.lang.Math.abs;

public static long roundUp(long num, long divisor) {
int sign = (num > 0 ? 1 : -1) * (divisor > 0 ? 1 : -1);
return sign * (abs(num) + abs(divisor) - 1) / abs(divisor);
}
``````

or if both numbers are positive

``````public static long roundUp(long num, long divisor) {
return (num + divisor - 1) / divisor;
}
``````

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