compare two list of objects in Java to remove duplicate

Question

I have two list of Objects. I have framed this list by querying the database.

For Ex:

List<Employee> firstList={holDate,holName,createdby,empId}
List<Employee> seconList={holDate,holName,createdby,empId}

Now, I need to compare holDate, holName of firstList with holDate, holName of secondList. If holDate, holName of firstList not found in secondList, I need to add that in separate list.

The list may be in any order.

NOTE: empId is a primary key column.

Update - what I've tried:

for(Employee emp:firstList) { 
    for(Employee tgtEmp:seconList) {  
        if((emp.getHolDate()!=tgtEmp.getHolDate())&& (emp.getHolName()!=tgtEmp.getHolName())){ 
            printList.add(emp); break; 
        } 
    }
}

Sample List Values:

firstList={{2015-08-15,"Independence Day","e1","Empl"},{2015-01-26,"Republic Day","e1","Empl"},{2015-09-20,"Memorial Day","e1","Empl"}}
seconList={{2015-08-15,"Independence Day","e1","Emp2"},{2015-10-25,"Thanks Giving Day","e1","Emp2"}}

Here, newlist should have all the values which is available in seconList and "RepublicDay","MemorialDay" from firstList

What is `Employee`? Does it have a custom `equals` and `hashcode` method, cause it would really easy then to just use `List#removeAll` or `List#retainAll` to identify the duplicates. Of course, you could just both of them into some kind of `Set`... — MadProgrammer, Jul 22 '15 at 07:24
You did any research before asking question? See plenty of question you can get in stackoverflow — Subodh Joshi, Jul 22 '15 at 07:26
Hi Renjith, pls find below snippet
for(Employee emp:firstList){ for(Employee tgtEmp:seconList){ if((emp.getHolDate()!=tgtEmp.getHolDate())&& (emp.getHolName()!=tgtEmp.getHolName())){ printList.add(emp); break; } } } — iShower, Jul 22 '15 at 07:26

score 1 · Accepted Answer · answered Jul 22 '15 at 07:51

1

Check this

 for (Employee emp : firstList) {
        boolean found=false;
        for (Employee tgtEmp : seconList) {
            if ((emp.getHolDate().equals(tgtEmp.getHolDate())) && (emp.getHolName().equals(tgtEmp.getHolName()))) {
                found=true;
                break;
            }
        }
        if(!found){
            printList.add(emp);
        }
    }

answered Jul 22 '15 at 07:51

vels4j

11,208
5
38
63

Is that okay to use this method if the size of list is very large? what will be the performance? – Coding world Jun 17 '22 at 07:16
@Codingworld you can use Objects.equals aswell – vels4j Jun 18 '22 at 08:30

score 0 · Answer 2 · answered Mar 02 '18 at 07:49

0

I think the above answer is not generically. Think if you add any new field on the Emp object then you need to update the equals method. If you are open to accepting new solution then please consider the below answer

Assert List in Junit

answered Mar 02 '18 at 07:49

Ganesa Vijayakumar

2,422
5
28
41

compare two list of objects in Java to remove duplicate

2 Answers2