How can JAVA obtain duplicate objects in a list?

To obtain the duplicate objects in a List, you can use the following method:

1. Iterate through the list using a loop, comparing each object to check for duplicates and adding the duplicates to another list.
2. List list = …; // Original List
   List duplicates = new ArrayList<>(); // List to store duplicate objects

   for (int i = 0; i < list.size(); i++) { T current = list.get(i); for (int j = i + 1; j < list.size(); j++) { T compare = list.get(j); if (current.equals(compare)) { if (!duplicates.contains(current)) { duplicates.add(current); } break; } } }

3. By utilizing the Stream API of Java 8 and combining it with the Collectors.groupingBy method, the objects can be grouped and then duplicate objects can be filtered out.
4. The original list is stored in a variable called “list”.
   A new list called “duplicates” is created by filtering out any repeated elements from the original list.

The type T in the above method is the object type to be compared, which can be replaced according to actual needs.