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strictfp keyword in java

A modifier called strictfp, which stands for strict floating-point, was added to Java version 1.2 as opposed to the base version. When executing operations on the floating-point variable, it is utilised in Java to restrict floating-point calculations and guarantee consistent outcomes across platforms.

Floating-point calculations are platform-dependent, which means that different output (floating-point values) are obtained when a class file is run on different platforms (16/32/64 bit processors). To address this issue, the strictfp keyword was introduced in JDK 1.2 by adhering to IEEE 754 standards for floating-point calculations.

Why we use strictfp Keyword

When a class file is run on various systems (16/32/64 bit processors), different output (floating-point values) are obtained because floating-point calculations are platform-dependent. The strictfp keyword, which complies with IEEE 754 standards for floating-point calculations, was added in JDK 1.2 to fix this problem.
Abstract methods cannot be used with strictfp. It can, however, be used with abstract classes/interfaces.
Since all interface methods are implicitly abstract, strictfp cannot be applied to any interface method.
The strictfp keyword is no longer required in Java 17 because all floating point expressions are strictly evaluated.

strictfp Keyword usage with classes

strictfp class Main{
   
   // Here, every concrete method is implicitly strictfp. 
}

strictfp Keyword usage with Interfaces

strictfp interface Main{
   
   // Here, every method becomes implicit.
   // Using strictfp during inheritance    
}

strictfp Keyword usage with variables

strictfp interface Main{
    double add();  
    strictfp double divide();  // C.T Error
}

strictfp Keyword usage with method

class Main{  
 strictfp void Add(){      //strictfp applied on method  

 }
}

Java example of strictfp keyword

 // Java example of strictfp keyword

class Main {
    public strictfp double add(){
        double a = 5e+05;
        double b = 3e+08;
        return a + b;
    }
    public static void main(String[] args){    
    	Main main = new Main();
        System.out.println(main.add());
    }
}

Output:

3.005E8

Illegal use for strictfp keyword

The strictfp keyword cannot be used on constructors, variables, or abstract methods.

class Main{  
 strictfp abstract void  Add(){ }     //strictfp applied on method  
}

class Main{  
 strictfp int   data=10;    //Modifier strictfp is not permitted here    
}

class Main{  
 strictfp int  add(){}    //Modifier strictfp is not permitted here    
}

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