To get started, let’s assume we have a list of objects that we want to paginate. We can utilize the Stream class from the Java Streams API to process this list in a stream-based manner.

Here’s an example code snippet that demonstrates how to implement pagination using the Java Streams API:

import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

public class Pagination {

    public List<Object> paginate(List<Object> list, int pageSize, int pageNumber) {
        int totalElements = list.size();
        int totalPages = (int) Math.ceil((double) totalElements / pageSize);

        if (pageNumber < 1 || pageNumber > totalPages) {
            throw new IllegalArgumentException("Invalid page number");
        }

        int start = (pageNumber - 1) * pageSize;
        int end = Math.min(start + pageSize, totalElements);

        return IntStream.range(start, end)
                .mapToObj(list::get)
                .collect(Collectors.toList());
    }
}

In the paginate method, we take three parameters - the list to be paginated, the pageSize which determines the number of elements per page, and the pageNumber which specifies the page to retrieve.

We calculate the total number of pages based on the total number of elements and the page size. If the provided page number is not within the valid range, we throw an IllegalArgumentException.

Next, we calculate the start and end indices of the sublist based on the page number and page size. We then create a stream of indices using IntStream.range and map each index to the corresponding object in the original list.

Finally, we collect the mapped objects into a new list using the Collectors.toList method, effectively creating our paginated result.

To use this pagination utility, you can create an instance of the Pagination class and call the paginate method, passing in your list, page size, and page number. For example:

Pagination pagination = new Pagination();
List<Object> paginatedList = pagination.paginate(yourList, 10, 2);

By implementing pagination using the Java Streams API, you can efficiently process large datasets without loading all the data into memory at once. This allows for better performance and improved resource management in your Java applications.

#java #pagination