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, strictfp keyword was introduced in 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 variables
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
Java
// Java program to illustrate strictfp modifier// Usage in Classes// Main classclass GFG { // Method 1 // Calculating sum using strictfp modifier public strictfp double sum() { double num1 = 10e+10; double num2 = 6e+08; // Returning the sum return (num1 + num2); } // Method 2 // Main driver method public static void main(String[] args) { // Creating object of class in main() method GFG t = new GFG(); // Here we have error of putting strictfp and // error is not found public static void main method System.out.println(t.sum()); }} |
Output:
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