Java 8 — BiConsumer | Code Factory

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Normal Consumer can take only one input argument and perform required operation and won’t return any result.

But sometimes our programming requirement to accept 2 input values and perform required operation and not required to return any result. Then we should go for BiConsumer.

BiConsumer is exactly same as Consumer except that it will take 2 input arguments.

@FunctionalInterface
public interface BiConsumer<T,U> {
    void accept(T t, U u);
    default BiConsumer<T,U> andThen(BiConsumer<? super T,? super U> after) { }
}

Program to accept 2 String values and print result of concatenation by using BiConsumer :

package com.codeFactory.biconsumer;
import java.util.function.BiConsumer;
public class Test {
 public static void main(String... args) {
  BiConsumer<String, String> c = (s1, s2) -> System.out.println(s1 + s2);
  c.accept("Code", "Factory");
 }
}

Output :

CodeFactory

Demo Program to increment employee Salary by using BiConsumer :

package com.codeFactory.biconsumer;
import java.util.ArrayList;
import java.util.function.BiConsumer;
class Employee {
 String name;
 double salary;
 
 Employee(String name, double salary) {
  this.name = name;
  this.salary = salary;
 }
@Override
 public String toString() {
  return "Employee [name=" + name + ", salary=" + salary + "]";
 }
}
public class Test {
 public static void main(String... args) {
  ArrayList<Employee> i = new ArrayList<>();
  populate(i);
  
  System.out.println("Before Increment :");
  print(i);
  
  BiConsumer<Employee, Double> c = (e, d) -> e.salary += d;
  for(Employee e : i) {
   c.accept(e, 750.0);
  }
  
  System.out.println("After Increment :");
  print(i);
 }
 
 private static void populate(ArrayList<Employee> i) {
  i.add(new Employee("Narendra", 1000));
  i.add(new Employee("Amit", 2000));
  i.add(new Employee("Vijay", 3000));
  i.add(new Employee("Yogi", 4000));
 }
 
 private static void print(ArrayList<Employee> i) {
  for(Employee e : i) {
   System.out.println(e);
  }
 }
}

Output :

Before Increment :
Employee [name=Narendra, salary=1000.0]
Employee [name=Amit, salary=2000.0]
Employee [name=Vijay, salary=3000.0]
Employee [name=Yogi, salary=4000.0]
After Increment :
Employee [name=Narendra, salary=1750.0]
Employee [name=Amit, salary=2750.0]
Employee [name=Vijay, salary=3750.0]
Employee [name=Yogi, salary=4750.0]

Comparison Table between One argument and Two argument Functional Interfaces :