Java 8 - BiConsumer Functional Interface

In this article, we will discuss pre-defined Functional Interface in Java 1.8 version for performing operation (processing) based on 2 input arguments passed but it won’t return any value after processing i.e.; BiConsumer Functional Interface

1. BiConsumer Functional Interface:

This Functional Interface has one abstract method called void accept(T t, U u); which
Step 1 :- accepts 2 input arguments of any data-type
Step 2 :- performs some operation or processes based on the 2 input arguments passed
Step 3 :- And doesn’t return result after processing (operation)
Below is the BiConsumer Functional Interface containing accept(); method along with other default & static methods

package java.util.function;

import java.util.Objects;

@FunctionalInterface
public interface BiConsumer<T, U> {

    /**
     * Performs this operation on the given arguments.
     *
     * @param t the first input argument
     * @param u the second input argument
     */
    void accept(T t, U u);

    // other default and static methods
}

2. Examples for BiConsumer Functional Interface :

Example 1 – program to print Student info along with increased grace marks of 5 for wrong question in the exam

package net.bench.resources.biconsumer.example;

import java.util.function.BiConsumer;

class Student {

	// member variables
	String name;
	int marks;

	// public constructor
	public Student(String name, int marks) {
		super();
		this.name = name;
		this.marks = marks;
	}
}

public class StudentResult {

	public static void main(String[] args) {

		// lambda expression to add grace marks to student using BiConsumer FI
		BiConsumer<Student, Integer> c = (s, i) -> s.marks = s.marks + 5;

		// create Student object with name and initial marks
		Student[] sArray = {
				new Student("Vijay", 92),
				new Student("Ajith", 78),
				new Student("Vikram", 66),
				new Student("Surya", 54),
				new Student("Karthi", 43),
				new Student("Arya", 31)
		};

		// invoke BiConsumer FI, iterating through all Students
		for(Student s : sArray) {
			c.accept(s, 5);
		}

		// printing to console
		for(Student s : sArray) {
			System.out.println("Name : " + s.name + "\tMarks : " + s.marks);
		}
	}
}

Output:

Name : Vijay	Marks : 97
Name : Ajith	Marks : 83
Name : Vikram	Marks : 71
Name : Surya	Marks : 59
Name : Karthi	Marks : 48
Name : Arya	Marks : 36

Example 2 – program to add 2 Integers using BiConsumer and also printing to console at the same time

package net.bench.resources.biconsumer.example;

import java.util.function.BiConsumer;

public class AddTwoNumbersUsingBiConsumer {

	public static void main(String[] args) {

		// lambda expression to add 2 numbers using BiConsumer FI
		BiConsumer<Integer, Integer> bc = 
				(i, j) -> System.out.println(i + " + " + j + " = " + (i+j));

				// add 2 numbers invoking above lambda expression
				bc.accept(7, 3);
				bc.accept(19, 2);
				bc.accept(20, 10);
				bc.accept(15, 25);
				bc.accept(1, 9);
	}
}

Output:

7 + 3 = 10
19 + 2 = 21
20 + 10 = 30
15 + 25 = 40
1 + 9 = 10

3. Difference between Consumer and BiConsumer Functional Interface :

Consumer :- It accepts 1 input argument and does some operation on the input argument passed but doesn’t return any value
BiConsumer :- Whereas it accepts 2 input arguments and does some operation on the 2 input arguments passed and doesn’t return any value
So, it is simple if we want to perform some operation based on single input argument and do not want to return any value then go for Consumer Functional Interface
But in case if we require to do some operation (or processing) on 2 input arguments and do not want to return any value then BiConsumer Functional Interface is the best option

package net.bench.resources.biconsumer.example;

import java.util.function.BiConsumer;
import java.util.function.Consumer;

public class DifferenceInConsumerAndBiConsumer {

	public static void main(String[] args) {

		// 1. Consumer - lambda expression to print to console Square value of input
		Consumer<Integer> c = (i) -> System.out.println(
				"Square of " + i + " is : " + i*i
				);

		// 2. BiConsumer - lambda expression to add both input arguments and print to console
		BiConsumer<Integer, Integer> bc = (i,j) -> System.out.println(
				"Sum of (" + i + ", "+ j + ") is : " + (i+j)
				);

		// 1.A test for Consumer
		System.out.println("Consumer testing for printing Square value : \n");
		c.accept(8);
		c.accept(19);

		// 2.A test for BiConsumer
		System.out.println("\nBiConsumer testing for both numbers : \n");
		bc.accept(7, 3);
		bc.accept(19, 43);
	}
}

Output:

Consumer testing for printing Square value : 

Square of 8 is : 64
Square of 19 is : 361

BiConsumer testing for both numbers : 

Sum of (7, 3) is : 10
Sum of (19, 43) is : 62

References:

Happy Coding !!
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Java 8 – BiConsumer Functional Interface

1. BiConsumer Functional Interface:

2. Examples for BiConsumer Functional Interface :

3. Difference between Consumer and BiConsumer Functional Interface :

References:

1. BiConsumer Functional Interface:

2. Examples for BiConsumer Functional Interface :

3. Difference between Consumer and BiConsumer Functional Interface :

References:

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