1. What is Java Collection Framework? List out some benefits of the Collection framework.
Java Collection Framework is a collection of data structure tools with the best-optimized performance, for example, fetching data from ArrayList gives O(1) times complexity and updating data in LinkedList takes O(1) times complexity.
It provides many tools to manage your data like ArrayList, HashSet, LinkedHashSet, LinkedList, PriorityQueue, HashMap, etc.; every tool has pros and cons. Suppose we need to fetch the list of details of students from the Database who score more than 90%, So, we need a tool to store/update our data.
Java Collection Framework introduced in Java version 1.2. Java Collection Framework is a complete utility setup which is used by every Java Developer and also uses Object-Oriented Design Principles with the help of interfaces and abstract classes, this sets an example for developers to think in Object-Oriented Design.
2. What are the new Collection features in Java 8?
Java 8 adds more features to the collection framework, making the collection more powerful and flexible—for example, StreamAPI, default and static method for the interface, lambda expression, etc. Let’s discuss:
- Stream API: Stream is nothing flow of operation or say chain of operations. One output becomes another input. Filter, transform, and aggregation in one flow.
- Default and Static Methods in Interfaces: Adding any number of static and default methods without breaking existing implementation.
3. What is the benefit of Generics in Collection Framework?
Generics are introduced in Java 1.5. It is the most important part of the collection framework. Generics bring type safety to the collection framework. Without type safety, errors are generated at runtime instead of compile time. Let’s discuss the benefits:
- Type-Safety: Ensuring a collection object can contain only specific types of objects, for example, ArrayList<String> can only hold string type of objects. Due to type-safety, we avoid ClassCastException and eliminate the need for explicit casting.
- Improved Readability: Generic code improves the readability of code and eliminates error-prone chances as the object type is explicitly defined.
4. What are the basic interfaces of Java Collections Framework?
Java Collection Framework is built up on some core interfaces and some specialised interfaces. Internally, it’s a complete hierarchical structure of interfaces where we define the behaviour. Let’s discuss the points.
Core Interfaces:
- Collection: This is the root interface where we define base (common) functionality, for example, add, remove, isEmpty, clear, addAll, toArray, etc. The collection interface also extends the Iterable interface.
- List: The list interface is more specific to maintaining an ordered collection. The advantage of a list is positional access, set objects at a specific index, etc.
- Set: The set interface does not allow duplicate elements. Internally it works on hashing principles.
- Map: The map interface allows you to add key-value objects. Here, the key is unique and duplicate values are allowed.
- Queue: The queue interface provides functionality like FIFO.
5. Why does Collection not extend Cloneable and Serializable interfaces?
6.