Question

i have a requirement in which i will retrieve all the records from the DB in a sorted form. These records will be sorted by “EnteredIds” field in DB.I am getting these records perfectly. I am placing these records in Map. So certainly I will have my map like :

<field1, EnteredId1> 
<field4, EnteredId1> 
<field3, EnteredId1> 
<field2, EnteredId1> 
<field6, EnteredId2> 
<field1, EnteredId2> 
<field2, EnteredId2> 

where EnteredId is in sorted form (i.e 1,1,1,1,2,2,2,…).
Now I want another list which will have objects according to the EnteredIds Like

Object1 will contain 4 records having EnteredId = EnteredId1.
Object2 will contain 3 records having EnteredId = EnteredId2.

and so on..
I have tried it using Map but the logic seems to be very much time consuming and very less optimized.

Please help..
Thanks in advance..

Answer 1

Although I still don’t fully understand your question, I’ll try an attempt to answer it.

I assume you have a map like this:

field1->id1
field2->id1
field3->id1
field4->id2
...

I further assume you want to get it the other way round, i.e.

id1 -> field1, field2, field3
id2 -> field4
...

This could be achieved by using a Map<Id,List<Field>> or better a MultiMap which Google Guava or Apache Commons Collections provide.