Extract Multiline Lambda Expression while using ForEach while iterating a Map in Java 8

Atul :

I am iterating a map like below using Java 8 with forEach

Map<Integer,String> testMap = new HashMap<>();
testMap.put(1, "Atul");
testMap.put(2, "Sudeep");
testMap.put(3, "Mayur");
testMap.put(4, "Suso");

testMap.entrySet().forEach( (K)-> {         
                System.out.println("Key ="+K.getKey()+" Value = "+K.getValue());
                System.out.println("Some more processing ....");            
            }

    );

My question is :

1) How do we extract a method out of forEach while processing in a map?

2)That is, the portion of code inside forEach should be wrapped inside method:

        System.out.println("Key ="+K.getKey()+" Value = "+K.getValue());
        System.out.println("Some more processing ....");    

3) I understand the forEach method in this case expects a Consumer Functional Interface` which has below signature -

void accept(T t); 

4) So what I want is something like this :

   //declare a consumer object 
   Consumer<Map.Entry<Integer,String>> processMap = null;

  // and pass it to ForEach 
  testMap.entrySet().forEach(processMap);

5) Can we achieve this?

davidxxx :

I understand the forEach method in this case expects a Consumer Functional Interface` which has below signature

forEach() expects indeed a Consumer but to process a Consumer you don't need necessarily a Consumer. What you need is a method that respects the input/output of the Consumer functional interface, that is Entry<Integer,String> input / void output.

So you could just invoke a method that has as parameter the Entry :

testMap.entrySet().forEach(k-> useEntry(k)));

or

testMap.entrySet().forEach(this::useEntry));

with useEntry() such as :

private void useEntry(Map.Entry<Integer,String> e)){        
    System.out.println("Key ="+e.getKey()+" Value = "+e.getValue());
    System.out.println("Some more processing ....");                        
}

Declaring a Consumer<Map.Entry<Integer,String>> that you pass to forEach() such as :

Consumer<Map.Entry<Integer,String>> consumer = this::useEntry;
//...used then :
testMap.entrySet().forEach(consumer);

makes sense only if the consumer in your forEach() is designed to be variabilized in a some way (computed/passed by the client or anyway).
If you are not in this case and that you use a Consumer, you finally made things more abstract and complicated than it is effectively required.