Android™ How to Program, Second Edition

Math Class Constants PI and E

Class Math declares two fields that represent commonly used mathematical constants—Math.PI and Math.E. Math.PI (3.141592653589793) is the ratio of a circle’s circumference to its diameter. Math.E (2.718281828459045) is the base value for natural logarithms (calculated with static Math method log). These fields are declared in class Math with the modifiers public, final and static. Making them public allows you to use these fields in your own classes. Any field declared with keyword final is constant—its value cannot change after the field is initialized. PI and E are declared final because their values never change. Making these fields static allows them to be accessed via the class name Math and a dot (.) separator, ...