Java collections Interview Questions

A Java collection is a group of individual types of objects that are represented in a single unit. Java also helps to provide the different collections of the framework which helps to define different classes and the interfaces to represent all the group of objects in a single unit.

The following are some of the types of the Java Collections:

• Interfaces
• Classes
• Algorithm

The interfaces in Java Collections helps to provide the hypothetical data type to represent all the Java Collections framework. The main motto of the interface is to allow Java Collections to manipulate freedom from the details of their representation.

The following are some of the types of interfaces used in the Java collection and they are:

• Collection interface
• List interface
• Set interface
• Queue interface
• Dequeue interface
• Map interface

The classes in Java are generally the types of application or the collection of the interface. These types of classes mainly refer to the data structure that is used again and again.

The algorithm in the Java Collections framework refers to the methods that are used to prefer various types of operations. This includes searching and sorting of the objects that help to implement the collection interfaces.

The main use of the list interface is to allow the Java Collections to define an ordered collection with the duplicates. The list interface helps to add all the position-oriented elements and the new list Iterator that will help to enable the list to become bi-directional.

The following are some of the main classes of the list interfaces:

• Stack
• Vector
• Array list
• Linked list

The main work of the set interface is to extend the Java Collections framework. At this moment, it will also make sure that if there is any of the duplications of the elements.

The following are some of the classes implemented in the set interfaces:

• Enum set
• Hash set
• Linked Hash set
• Tree Set

A map is basically a type of container that stores the elements along with the keys in the Java Collections. These types of keys are basically indexes. In the map interfaces, the keys can be of any of the objects. A map doesn’t contain any of the duplicate keys.

The following are some of the implementing classes in the map interfaces:

• Hash Map
• Hash table
• Enum Map
• Identity Hash Map
• Linked Hash map
• Properties

The following are some of the different types of collections views being provided by the Map interface:

• Key set view
• Value Set view
• Entry set view

A queue is basically a first in and first out data structure. The elements are basically are added at the end of the queue and are automatically removed from the starting of the queue.

The Iterator mainly helps to remove all the underlying collections during the Iteration. The caller can easily remove the Iteration by following the command, which is Remove ().

The following are some of the different types of ways where you can iterate over a list:

• Iterate loop
• For loop
• For loop advances
• While loop

An enumerator is the type of interface in the Java Collections framework. Using the enumeration you can easily traverse the collections. But you can’t do any of the modifications of the collections while you are traversing it.

Deque is the type of the double-ended queue that basically helps and supports the addition and removal of the elements from either end of the data structure.

The following are some main features of the Java Collections framework:

• Deque has the feature to provide the support of the resizable array and will also help to free the array so that the array can grow according to the usage.
• Any of the concurrent access is not being supported by the multiple threads or the Deque.