[FIXED] how to Implementation of intersection, difference and union with List<HashMap<String, Object>> in java

Issue

I want to get intersection and difference between List<HashMap<String, Object>> but below code just show true or false.

I want to get difference like [{prodCode=KR7279570006, accountNum=20101834049, orgCode=C1AACQ0000}]

I want to get intersection like [{prodCode=KR7020150009, accountNum=20402786856, orgCode=C1AACQ0000}, {prodCode=KR7020150009, accountNum=20101834049, orgCode=C1AACQ0000}]

List<HashMap<String, Object>>  stockListInDb = 
[{prodCode=KR7020150009, accountNum=20402786856, orgCode=C1AACQ0000}, 
{prodCode=KR7020150009, accountNum=20101834049, orgCode=C1AACQ0000}]
    
List<HashMap<String, Object>> presentedStockList = 
[{prodCode=KR7020150009, accountNum=20402786856, orgCode=C1AACQ0000}, 
{prodCode=KR7020150009, accountNum=20101834049, orgCode=C1AACQ0000}, 
{prodCode=KR7279570006, accountNum=20101834049, orgCode=C1AACQ0000}]
    
System.out.println("새로운 주식은 " + presentedStockList.removeAll(stockListInDb) );
System.out.println("홀딩한 주식은 " + stockListInDb.retainAll(presentedStockList));

새로운 주식은 true
홀딩한 주식은 true

Solution

I have also tried retainAll, but it's not working instead of using this use: If you want the intersection of List1 and List 2 it will remove all elements from the list1 that are present in list 2. if you want the differencece just replace the List1 to list2 and vice versa.

List1.stream().filter(List2::contains).collect(Collectors.toList());

Answered By - Sandeep Kumar Nat
Answer Checked By - Katrina (JavaFixing Volunteer)