Basic Mathematics in Java

The public final class Math contains all the basic numerical functions and constants.

Math.E (the base of the natural logarithms), Math.PI (ratio of circumference of a circle to its diameter).

Math.ceil, Math.floor do the expected operations, mapping doubles to ints.

Math.random, when first called creates a new PRN generator (thread-safe singleton, java.util.Random). If numerous threads are involved, multiple PRN generators ought to be instantiated. Returns a double value in the range [0,1).

Beware of the int division wall. This basically means 1/5 returns 0 since int/int returns floor(int). To avoid the "int division wall" cast to double, use decimals or write 1.0/5 to get result of division as a double.