ToDoubleFunction Interface is a part of the java.util.function package which is introduced in Java 8. It is an in-built Functional Interface. This function expect an argument as an input and produces a double-valued result. As it is a functional interface, it can be used assignment target for lambda expression or method reference. In this post, we are going to see several implementations of ToDoubleFunction Interface by using different examples.
ToDoubleFunction Interface in Java 8 with Examples...!!! Share on X
Look at ToDoubleFunction Javadoc description below:
ToDoubleFunction Interface contains below method:
applyAsDouble
Let’s discuss these methods:
applyAsDouble
This method performs operation on the given argument and return the double-valued result.
double applyAsDouble(T value);
Lets understand above mentioned method through below example:
Example. ‘applyAsDouble’ method
import java.util.function.ToDoubleFunction;
public class ToDoubleFunctionInterfaceJava8Example1 {
public static void main(String[] args) {
System.out.println("ToDoubleFunction Interface - 'applyAsDouble' example \n");
//1. anonymous implementation
ToDoubleFunction <Integer> anonymousObj = new ToDoubleFunction <Integer> () {
@Override
public double applyAsDouble(Integer value) {
return value * 25;
}
};
//2. lambda implementation of toDoubleFuncObj object
ToDoubleFunction <Integer> lambdaObj = value -> value * 25;
//1
System.out.println("Result : " + anonymousObj.applyAsDouble(5));
//2
System.out.println("Result : " + lambdaObj.applyAsDouble(5));
}
}
Output:
ToDoubleFunction Interface - 'applyAsDouble' example Result : 125.0 Result : 125.0
Java 8 ToDoubleFunction Interface is an absolute useful addition as part of ‘Functional Interfaces’ and can serve variety of purposes. It is quite powerful as it can be used as a higher order functions through lambda functions and above examples could help you to get better idea on how to implement it.
ToDoubleFunction Interface in Java 8 with Examples...!!! Share on X
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