strictfp keyword in java

Last Updated : 21 Mar, 2024

In Java, the strictfp is a modifier that stands for strict floating-point which was not introduced in the base version of Java as it was introduced in Java version 1.2. It is used in Java for restricting floating-point calculations and ensuring the same result on every platform while performing operations in the floating-point variable.
Floating-point calculations are platform-dependent i.e. different output (floating-point values) is achieved when a class file is run on different platforms (16/32/64-bit processors). To solve this type of issue, the strictfp keyword was introduced in the JDK 1.2 version by following IEEE 754 standards for floating-point calculations.

Note: strictfp modifier is used with classes, interfaces, and methods only but is not applicable to apply with variables as illustrated below:

Illustration 1: Keyword usage with classes

strictfp class Test {

 // All concrete methods here are implicitly strictfp. 
}

Illustration 2: Keyword usage with Interfaces

strictfp interface Test { 
 // All methods here becomes implicitly 
 // strictfp when used during inheritance. 
}

class Car {
 // strictfp applied on a concrete method 
 strictfp void calculateSpeed(){}
}

Illustration 3: Keyword usage with Abstract method in an Interface

strictfp interface Test {
 double sum();

 // Compile-time error here
 strictfp double mul(); 
}

Some conclusions can be drawn from the above illustrations as follows:

When a class or an interface is declared with strictfp modifier, then all methods declared in the class/interface, and all nested types declared in the class, are implicitly strictfp.
strictfp cannot be used with abstract methods. However, it can be used with abstract classes/interfaces.
Since methods of an interface are implicitly abstract, strictfp cannot be used with any method inside an interface.
From Java 17 version, strictfp keyword is NOT required explicitly as all floating-point expressions are strictly evaluated.

Example:

Output