Consumer and Bi-consumer functional interface java

Functional Interface:

Functional interface is an interface that contains only one abstract method. A functional interface can have any number of default methods.
Consumer, Bi-consumer, Runnable are some example of functional interface. Annotation @FunctionalInterface is not mandatory however @FunctionalInterface annotation is used to ensure that the functional interface can’t have more than one abstract method

Consumer :

@FunctionalInterface

public interface Consumer < T > {

    void accept(T t);

}

 public class ConsumerImpl {

public static void main(String args[]) {

List<String> strList = Arrays.asList("one","two","three");

strList.forEach(new Consumer<String>() {

@Override

public void accept(String str) {

System.out.println(str);

}

});

}

}

OR Lambda format

java.lang.Iterable.forEach() method internally uses Consumer interface. 

public class ConsumerImpl {

public static void main(String args[]) {

List<String> strList = Arrays.asList("one","two","three");

strList.forEach(x->System.out.println(x));

}

}

Bi-Consumer : 

@FunctionalInterface

public interface BiConsumer<T, U>

Sample code:

public class BiConsumerImpl {

public static void main(String args[]) {

Map<Integer,String> map = new HashMap<>();

map.put(1, "one");

map.put(2,"two");

map.put(3,"three");

map.forEach(new BiConsumer<Integer, String>() {

@Override

public void accept(Integer arg0, String arg1) {

System.out.println(arg0 +"---"+arg1);

}

});

}

}