Last Updated : 11 Jul, 2025
The
DoubleFunction Interfaceis a part of the
java.util.functionpackage which has been introduced since Java 8, to implement
functional programmingin Java. It represents a function which takes in a double-valued argument and produces a result of type
R. This functional interface takes in only one generic, namely:-
The lambda expression assigned to an object of DoubleFunction type is used to define its
apply()which eventually applies the given operation on its only argument. It is similar to using an object of type
Function<Double, R>. The DoubleFunction interface has only one function:
apply()This method accepts a double-valued argument and gives a result of type R.
Syntax:R apply(double value)Parameters:
This method takes in one parameter
valuewhich is a double-valued argument.
Returns:This method returns a value of type
R. Below is the code to illustrate apply() method:
Program Java
import java.util.function.DoubleFunction;
public class Main {
public static void main(String args[])
{
DoubleFunction<Integer> ob = a -> (int)(a * 10);
// Using apply() method
System.out.println(ob.apply(3.2));
}
}
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