Implement DoubleConsumer Using Lambda Expression in Java

DoubleConsumer is a functional interface from java.util.function package. This functional interface accepts a single double-valued argument as input and produces no output. This interface can be used as an assignment target for a lambda expression or method reference. DoubleConsumer contains one abstract method: accept() and one default method: andThen().

Syntax

@FunctionalInterface
public interface DoubleConsumer {
   void accept(double value);
}

Example-1

import java.util.function.DoubleConsumer;

public class DoubleConsumerLambdaTest1 {
   public static void main(String args[]) {
      DoubleConsumer increment = doubleVal -> {       // lambda expression
         System.out.println("Incrementing " + doubleVal + " by one");
         System.out.println("Current Value : "+ (doubleVal+1));
      };
      DoubleConsumer decrement = doubleVal -> {       // lambda expression
         System.out.println("Decrementing " + doubleVal + " by one");
         System.out.println("Current Value : " + (doubleVal-1));
      };
      DoubleConsumer result = increment.andThen(decrement);
      result.accept(777);
   }
}

Output

Incrementing 777.0 by one
Current Value : 778.0
Decrementing 777.0 by one
Current Value : 776.0

Example-2

import java.util.Arrays;
import java.util.function.DoubleConsumer;

public class DoubleConsumerLambdaTest2 {

   public static void main(String[] args) {
      double[] numbers = {4.7d, 7d, 8.2d, 6.8d, 10.5d, 3.2d};
       DoubleConsumer dconsumer = d -> System.out.print(d + " ");   // lambda expression
       Arrays.stream(numbers).forEach(dconsumer);
   }
}

Output

4.7 7.0 8.2 6.8 10.5 3.2