Reshma Bidikar

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

The DoubleConsumer interface provides a method called accept. It accepts a single parameter of double data type. It does not return anything, it returns a void. So it operates via side effects i.e. it modifies the parameter passed in. The DoubleConsumer interface is a specialization of the Consumer interface. While the Consumer interface accepts any data type, the DoubleConsumer interface accepts a Double value. To see an example of the Consumer interface, refer tothis blog post.

DoubleConsumer Example

Consider the following code snippet:

public class DoubleConsumerDemo {

  public static void main(String args[]) {
    DoubleConsumer squareGenerator = (num) -> System.out.println(num*num);
    double input = 5.0;
    squareGenerator.accept(input);
  }

}

Here, the DoubleConsumer.accept method accepts a double value. It squares it (i.e. multiplies it by itself) and prints the result. So when the above code is executed, it will print the following output:

25.0

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