Java 8 | ObjDoubleConsumer Interface with Example

The ObjDoubleConsumer Interface is a part of the java.util.function package which has been introduced since Java 8, to implement functional programming in Java. It represents a function which takes in two arguments and produces a result. However these kind of functions don't return any value. Hence this functional interface takes in one generic namely:-

• T: denotes the type of the input argument to the operation

The lambda expression assigned to an object of ObjDoubleConsumer type is used to define its accept() which eventually applies the given operation on its argument. It takes in a double-valued and a T-valued argument and is expected to operate without any side effects. It is more like using an object of type BiConsumer<T, Double> except the fact that one is a reference and one is a primitive data type in this case. Hence we will be obtaining one reference and one value when this function is called.

Functions in ObjDoubleConsumer Interface

The ObjDoubleConsumer interface consists of the following two functions:

1. accept()

This method accepts two values and performs the operation on the given arguments. Syntax:

void accept(T t, double value)

Parameters: This method takes in two parameters:

• t- the first input argument
• value- the second input argument

Return Value: This method does not return any value. Below is the code to illustrate accept() method: Program: Java

// Java code to demonstrate
// accept() method of ObjDoubleConsumer Interface

import java.util.Arrays;
import java.util.List;
import java.util.function.ObjDoubleConsumer;
import java.util.stream.Stream;

public class GFG {
    public static void main(String args[])
    {

        // Get the list from which
        // the Interface is to be instantiated.
        List<Integer>
            arr = Arrays.asList(3, 2, 5, 7, 4);

        // Instantiate the ObjDoubleConsumer interface
        ObjDoubleConsumer<List<Integer> >
            func = (list, num) ->
        {
            list.stream()
                .forEach(
                    a -> System.out.println(a * num));
        };
        func.accept(arr, 2.0);
    }
}