How to round up integer division and have int result in Java? [duplicate]

Question

Use Math.ceil() and cast the result to int:

• This is still faster than to avoid doubles by using abs().
• The result is correct when working with negatives, because -0.999 will be rounded UP to 0

Example:

(int) Math.ceil((double)divident / divisor);

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;
}

Another one-liner that is not too complicated:

private int countNumberOfPages(int numberOfObjects, int pageSize) {
    return numberOfObjects / pageSize + (numberOfObjects % pageSize == 0 ? 0 : 1);
}

Could use long instead of int; just change the parameter types and return type.

Google's Guava library handles this in the IntMath class:

IntMath.divide(numerator, divisor, RoundingMode.CEILING);

Unlike many answers here, it handles negative numbers. It also throws an appropriate exception when attempting to divide by zero.

(message.length() + 152) / 153

This will give a "rounded up" integer.

long numberOfPages = new BigDecimal(resultsSize).divide(new BigDecimal(pageSize), RoundingMode.UP).longValue();