Create multiple Lists from one (Group List’s Objects by a specific field)

Given that I have the array of :

List<CustEnt> bulkList= CustRepo.fetchData();
//System.out.println(bulkList) -->

gives me :

    CustEct(name:"kasis",age:24,surname:"kumar"),CustEct(name:"samika",age:50,surname:"sharma"),CustEct(name:"manoj",age:84surname:"kumar")
OR
bulkList.get(1) --> CustEct(name:"kasis",age:24,surname:"kumar")

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I want to create a new array which is grouped by the 3rd parameter of surname object. So that my array becomes

ArrayFinal = [CustEct(name:"kasis",age:24,surname:"kumar"),CustEct(name:"samika",age:50,surname:"sharma")],CustEct(name:"manoj",age:84surname:"kumar")

So that when we do .get(1) we would get object of kasis and samika.

Need the help in respective to java 8. I heard that we can use the Map ,but can anyone give the small code sample or any other implementation guide.

Answer

A Map tracks key-value pairs.

• Your key is the surname string.
• Your value is a list of the CustEnt objects carrying that surname.

Map<String, List<CustEnt>>

Modern syntax with streams and lambdas makes for brief code to place your objects in a map.

Something like:

Map<String, List<CustEnt>> map = originalList.stream.collect(Collectors.groupingBy(CustEnt::getSurename));