1. Introduction

Pagination is a technique that is often used to handle large sets of data by dividing them into smaller, more manageable parts or ‘pages’. In Java, you can also paginate a Map by converting it to a List of Map.Entry objects and then using the subList method for pagination.

2. Program Steps

1. Import the required libraries.

2. Create a Map of elements.

3. Convert the Map to a List of Map.Entry objects.

4. Define the page size.

5. Calculate the total number of pages.

6. Loop through each page and display the elements of each page using the subList method.

3. Code Program

// Step 1: Import the required libraries
import java.util.*;
import java.util.stream.Collectors;

public class MapPagination {

    public static void main(String[] args) {

        // Step 2: Create a Map of elements
        Map<Integer, String> itemsMap = new LinkedHashMap<>();
        for (int i = 1; i <= 25; i++) {
            itemsMap.put(i, "Item " + i);
        }

        // Step 3: Convert the Map to a List of Map.Entry objects
        List<Map.Entry<Integer, String>> entryList = new ArrayList<>(itemsMap.entrySet());

        // Step 4: Define the page size
        int pageSize = 5;

        // Step 5: Calculate the total number of pages
        int totalPages = (int) Math.ceil((double) entryList.size() / pageSize);

        // Step 6: Loop through each page and display the elements of each page using the subList method
        for (int i = 0; i < totalPages; i++) {
            int fromIndex = i * pageSize;
            int toIndex = Math.min(fromIndex + pageSize, entryList.size());
            List<Map.Entry<Integer, String>> page = entryList.subList(fromIndex, toIndex);
            System.out.println("Page " + (i + 1) + ": " + page.stream().collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue)));
        }
    }
}

Output:

Page 1: {1=Item 1, 2=Item 2, 3=Item 3, 4=Item 4, 5=Item 5}
Page 2: {6=Item 6, 7=Item 7, 8=Item 8, 9=Item 9, 10=Item 10}
Page 3: {11=Item 11, 12=Item 12, 13=Item 13, 14=Item 14, 15=Item 15}
Page 4: {16=Item 16, 17=Item 17, 18=Item 18, 19=Item 19, 20=Item 20}
Page 5: {21=Item 21, 22=Item 22, 23=Item 23, 24=Item 24, 25=Item 25}

4. Step By Step Explanation

Step 1: Import the necessary classes and interfaces from the java.util package.

Step 2: Create a Map and initialize it with 25 key-value pairs.

Step 3: Convert the Map to a List of Map.Entry objects to apply pagination.

Step 4: Define the page size which signifies the number of elements each page will contain.

Step 5: Calculate the total number of pages needed to paginate all elements with the defined page size.

Step 6: Loop through each page, calculate the fromIndex and toIndex for the subList method, create a subList for each page, and display the elements in Map format for each page.