java restrict List items [duplicate]

Question

I am new to java. I have 5000 items in a list. I want to loop through the list so that I can get 100 items at a time. I have the following code:

   List<ProcessQueueBatch> processQueueBatchList = 
        Repository.getProcessQueue("Jor");
for (ProcessQueueBatch queueBatch : processQueueBatchList) 

   {
    // do some processing



   }

I want to do the processing of first 100 items in the list and then the next 100 items and then again next 100 items until all 5000 items are processed. I have total 5000 items in the list. How can I modify my for loop or list so that I can get 100 items at a time.

any help will be greatly appreciated.

A cycle of iteration only tackles one element at a time by default. Unless you want to do some weird list slicing, I'm not sure I see much value in this approach. — Makoto
– Makoto, Commented Aug 14, 2017 at 22:26
You can define an index variable an using if condition to help you seperate the loop. — TuyenNTA
– TuyenNTA, Commented Aug 14, 2017 at 22:28

Idos · Accepted Answer · 2017-08-14 22:26:50Z

0

You can use List.subList(int, int) to get the first K items from your processQueueBatchList like so:

int K = 100;
List<ProcessQueueBatch> newList = new ArrayList<>(processQueueBatchList.subList(0, K));

You should be able to take it from here...

answered Aug 14, 2017 at 22:26

Idos

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BeUndead · Accepted Answer · 2017-08-14 22:28:53Z

0

If your choice of List supports it, there's always List::subList.

There's also implementations using Streams. For example:

myList.stream()
        .skip(10) // Skip the first 'n' elements.
        .limit(100) // Limit the return size.
        .collect(Collectors.toList()); // Collect however you see fit.

Which would be helpful if you needed to do some filtering, as well.

answered Aug 14, 2017 at 22:28

BeUndead

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