The overloaded methods of groupingBy are: Vector is thread-safe, but ArrayList and LinkedList are not. A Computer Science portal for geeks. This concept of grouping is the same as the ‘group by’ clause in SQL which takes an attribute, or a calculated value derived from attribute(s), to divide the retrieved records in distinct groups. Besides ArrayList and LinkedList, Vector class is a legacy collection and later was retrofitted to implement the List interface. 2. A list of polymorphic objects is not a problem though. Java 8 simplified the grouping of objects in the collection based one or more property values using groupingBy() method.. CompareToBuilder 4. Here Coding compiler sharing a list of 40 Java Objective Questions and Answers for freshers and experienced Java developers.We hope that these Java MCQ Questions will help you to crack your next Java interview.All the best for your future and happy Java learning. Gson is flexible and accepts List and Array implementations on the Java side. Attribute Description; cn: The cn (or Common-Name) is a single-value attribute that is the object's relative distinguished name. Map