Java Programming: Strict Floating-Point Arithmetic: strictfp

Strict Floating-Point Arithmetic: strictfp: Learn Java Programming Tips

Although floating-point arithmetic in Java is defined in accordance with the IEEE-754 32-bit (float) and 64-bit (double) standard formats, the language does allow JVM implementations to use other extended formats for intermediate results. This means that floating-point arithmetic can give different results on such JVMs, with possible loss of precision. Such a behavior is termed non-strict, in contrast to being strict and adhering to the standard formats.

To ensure identical results are produced on all JVMs, the keyword strictfp can be used to enforce strict behavior for floating-point arithmetic. The modifier strictfp can be applied to classes, interfaces, and methods. A strictfp method ensures that all code in the method is executed strictly. If a class or interface is declared to be strictfp, then all code (in methods, initializers, and nested classes and interfaces) is executed strictly. If the expression is determined to be in a strictfp construct, it is executed strictly. However, note that strictness is not inherited by the subclasses or subinterfaces. Constant expressions are always evaluated strictly at compile time.