Java8 Primitive Consumer Interface examples| Functional Interface tutorials

Learn about primitive Consumers in java8 with examples.

#java.util.function.consumer Interface

Java 8 introduced different consumer interfaces in java.util.function package.

• IntConsumer
• LongConsumer
• DoubleConsumer

Consumer is an operation that accepts numeric values and outputs no result.

In my previous post, documented consumer tutorials.

#java8 IntConsumer class

IntConsumer is an interface defined in java.util.function package. It has only a single abstract method - accept() which takes an input value and returns nothing.

And also default method - andThen(IntConsumer after) - Returns aggregation consumer of called consumer with after consumer result.

import java.util.Arrays;
import java.util.function.IntConsumer;

public class Test {
    public static void main(String[] args)  throws Exception{
        IntConsumer consumer = value -> System.out.println(value);
        consumer.accept(51);
        consumer.accept(110);
        int[] numbers = {8,7,3,1};
        IntConsumer intConsumerFunction = value -> System.out.print(value+" ");
        Arrays.stream(numbers).forEach(intConsumerFunction);
    }
}

Output:

51
110
8 7 3 1

#java8 LongConsumer class

LongConsumer interface is defined in java.util.function package in java8.

It takes a long input value and output no result.

It has only one abstract method -accept()

Default method - andThen(LongConsumer after) - returns aggregate compose consumer of called consumer with the operation of after result consumer.

Following is a code for accept and andthen method Example

import java.util.function.LongConsumer;

public class Test {
    public static void main(String[] args)  throws Exception{
        LongConsumer longConsumer1 = (value ) -> { System.out.println(value); };
        longConsumer1.accept(5);
        LongConsumer longConsumer2 = ( value) -> { System.out.println(value); };
        longConsumer1.andThen(longConsumer2).accept(4);
    }
}

Output:

5
4
4

#Java8 DoubleConsumer class

DoubleConsumer is an inbuilt interface defined in java.util.function package in java8. It has only accept abstract method, takes a double value, and produces no output Also, It has the andThen default method.

import java.util.function.DoubleConsumer;

public class Test {
    public static void main(String[] args)  throws Exception{
        DoubleConsumer multiplyDoubleConsumer= (value) -> System.out.println(value*value);
        multiplyDoubleConsumer.accept(.5);
    }
}

Output:

0.25

#Conclusion

In this tutorial, Learn about primitive consumer interface types - IntConsumer, DoubleConsumer, LongConsumer functional interfaces with examples