Reshma Bidikar

In this blog post, I will be explaining how the Java 8 functional interface BiConsumer works. To know more about functional interfaces, you can refer this blog post.

The BiConsumer interface provides a method called accept. It accepts 2 parameters of any data type. It does not return anything, it returns a void. So it operates via side effects i.e. it modifies the parameters passed in. The BiConsumer interface is a specialization of the Consumer interface. To see an example of the Consumer interface, refer to this blog post.

BiConsumer example with Two Integer parameter

Consider the following code snippet:

public class BiConsumerDemo {

  public static void main(String args[]){ 
    BiConsumer<Integer,Integer> displaySum = (input1,input2) -> System.out.println("Sum of inputs is "+(input1+input2)); 
    displaySum.accept(4,8); 
  }
} 

Here, we have implemented the BiConsumer.accept method using a lambda expression. This accept method accepts 2 Integer arguments. It adds them iand prints the result to the console. So when this code is executed, it will print the following output:

Sum of inputs is 12

Consumer example with Integer and String as parameter

Consider the following code snippet:

public class BiConsumerDemo {

  public static void main(String args[]){ 
    BiConsumer<String,Integer> printConcatenatedValue = (input1,input2) -> System.out.println("Result of concatenating the inputs is "+(input1+input2)); printConcatenatedValue.accept("Hello World",5); 
  }
}

Again, we have implemented the BiConsumer.accept method using a lambda expression. This accept method accepts an Integer and a String value. It concatenates both the inputs using the + operator and prints the results. So when you execute this code, it will print the following output:

Result of concatenating the inputs is Hello World5

You can get the source code for this example along with the code for other Java 8 examples at the Github repository here.