absolute value : Java Glossary

absolute value

Math.abs will compute the absolute value of an int, long or double. It is x if x is positive, -x if x is negative and 0 if x is 0, ie. x considered as a positive value. You can code it yourself like this:

final int y = x >= 0 ? x : -x;

There is a fundamental problem with Math.abs. There is no corresponding positive value to Integer. MIN_VALUE and Long. MIN_VALUE, the most negative int and long respectively. Math. abs returns those values unchanged, i.e. negative.

You can strip the sign bit to avoid that problem. Then Long. MIN_VALUE becomes 0.

Learning More

Sun’s Javadoc on Math.abs : available:

on the web at java.sun.com
in the current JDK 1.6.0_17 or in the old JDK 1.5.0_22 on your local Windows J: drive.

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