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
– MadProgrammer, Commented Jul 22, 2015 at 7:24
You did any research before asking question? See plenty of question you can get in stackoverflow — Subodh Joshi
– Subodh Joshi, Commented Jul 22, 2015 at 7:26
Hi Renjith, pls find below snippet<br> for(Employee emp:firstList){ for(Employee tgtEmp:seconList){ if((emp.getHolDate()!=tgtEmp.getHolDate())&& (emp.getHolName()!=tgtEmp.getHolName())){ printList.add(emp); break; } } } — iShower
– iShower, Commented Jul 22, 2015 at 7:26

vels4j · Accepted Answer · 2015-07-22 07:51:20Z

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, 2015 at 7:51

vels4j

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2 Comments

Coding world Over a year ago

Is that okay to use this method if the size of list is very large? what will be the performance?

vels4j Over a year ago

@Codingworld you can use Objects.equals aswell

Ganesa Vijayakumar · Accepted Answer · 2018-03-02 07:49:39Z

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 2, 2018 at 7:49

Ganesa Vijayakumar

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