How to use the built-in CollectionUtils in Spring Boot.

Spring Boot comes with many built-in utility classes, among which CollectionUtils is a very commonly used utility class for manipulating and processing collections. Below is an example of how to use CollectionUtils.

1. Import the CollectionUtils class.
2. Include the CollectionUtils class from the org.springframework package.
3. Utilizing the methods in CollectionUtils:
4. Check if the collection is empty by creating a list of strings with an ArrayList and using CollectionUtils.isEmpty method.
5. Check if the collection is not empty by creating a list and using CollectionUtils.isNotEmpty() method.
6. Merge multiple collections into one collection:
   List list1 = new ArrayList<>();
   List list2 = new ArrayList<>();
   List mergedList = CollectionUtils.mergeArrays(list1, list2);
7. Remove the empty elements from the collection:
   List list = new ArrayList<>();
   list.add(“a”);
   list.add(null);
   list.add(“b”);
   CollectionUtils.filter(list, Objects::nonNull);
8. Remove elements from the collection that meet the given criteria:
   List list = new ArrayList<>();
   list.add(1);
   list.add(2);
   list.add(3);
   CollectionUtils.filter(list, num -> num % 2 == 0);
9. Iterate through the collection elements:
   List list = new ArrayList<>();
   list.add(“a”);
   list.add(“b”);
   CollectionUtils.arrayToList(list).forEach(System.out::println);
10. Retrieve the first element of the set:
    List list = new ArrayList<>();
    list.add(“a”);
    list.add(“b”);
    String firstElement = CollectionUtils.firstElement(list);
11. Obtain the last element of a collection:
    List list = new ArrayList<>();
    list.add(“a”);
    list.add(“b”);
    String lastElement = CollectionUtils.lastElement(list);

The above are some common method examples of CollectionUtils. Choose the appropriate method to manipulate the collection based on specific requirements.