File Name: collections in java interview questions and answers .zip
Without argument, java collections is one of the most important area where you will be tested in any position whether junior or senior. The scope is so much wide, that its almost impossible to cover all the questions. Yet based on my previous interviews, I am attempting to put as many as possible GOOD java collection interview questions you must know.
- Top 50 Java Collections Interview Questions You Need to Know
- 34 Java Collections Interview Questions
- [2020 Updated] Top 50 Java Collections Interview Questions and Answers
- Java Collections Interview Questions
In Java, collection interview questions are most asked by the interviewers. Here is the list of the most asked collections interview questions with answers.
Here are Java Collections Interview Questions for fresher as well as experienced candidates to get their dream job. A framework is a popular and readymade architecture that contains a set of classes and interfaces. Collection Framework is a grouping of classes and interfaces that is used to store and manage the objects. Java Collection framework can also be used for interfaces like Queue, Set, List, etc. Collections is a class consists of static methods that operate on collections.
Top 50 Java Collections Interview Questions You Need to Know
In Java, collection interview questions are most asked by the interviewers. Here is the list of the most asked collections interview questions with answers. Collection Framework is a combination of classes and interface, which is used to store and manipulate the data in the form of objects. Array and Collection are somewhat similar regarding storing the references of objects and manipulating the data, but they differ in many ways. The main differences between the array and Collection are defined below:.
Collection framework implements various interfaces, Collection interface and Map interface java. Map are the mainly used interfaces of Java Collection Framework. List of interfaces of Collection Framework is given below:. Collection interface: Collection java.
Collection is the primary interface, and every collection must implement this interface. List interface: List interface extends the Collection interface, and it is an ordered collection of objects.
It contains duplicate elements. It also allows random access of elements. Set interface: Set java. Set interface is a collection which cannot contain duplicate elements. It can only include inherited methods of Collection interface.
Queue interface: Queue java. Queue interface defines queue data structure, which stores the elements in the form FIFO first in first out. Dequeue interface: it is a double-ended-queue.
It allows the insertion and removal of elements from both ends. Map interface: A Map java. Map represents a key, value pair storage of elements. Map interface does not implement the Collection interface. It can only contain a unique key but can have duplicate elements. There are two interfaces which implement Map in java that are Map interface and Sorted Map.
Iterator traverses the elements in the forward direction only whereas ListIterator traverses the elements into forward and backward direction. The List and Set both extend the collection interface. However, there are some differences between the both which are listed below.
The differences between the both are listed below. BlockingQueue is an interface which extends the Queue interface. It provides concurrency in the operations like retrieval, insertion, deletion. While retrieval of any element, it waits for the queue to be non-empty. While storing the elements, it waits for the available space. BlockingQueue cannot contain null elements, and implementation of BlockingQueue is thread-safe.
If you change the value in the properties file, you don't need to recompile the java class. So, it makes the application easy to manage. It is used to store information which is to be changed frequently. Consider the following example. The hashCode method returns the same integer number if two keys by calling equals method are identical. If two objects do not produce an equal result by using the equals method, then the hashcode method will provide the different integer result for both the objects.
The equals method is used to check whether two objects are the same or not. It needs to be overridden if we want to check the objects based on the property.
For example, Employee is a class that has 3 data members: id, name, and salary. However, we want to check the equality of employee object by the salary. Then, we need to override the equals method. Two different keys with the same hash value are known as hash-collision. Two separate entries will be kept in a single hash bucket to avoid the collision.
There are two ways to avoid hash-collision. The default size of load factor is 0. So, 12 is the default capacity of Map. The Iterator in java which immediately throws ConcurrentmodificationException, if any structural modification occurs in, is called as a Fail-fast iterator. Fail-fats iterator does not require any extra space in memory. The length of an array can be obtained using the property of length whereas ArrayList does not support length property, but we can use size method to get the number of objects in the list.
Consider the following syntax:. Consider the following syntax to convert the ArrayList to the List object. We can obtain java ArrayList Read-only by calling the Collections. To reverse an ArrayList, we can use reverse method of Collections class. To sort the ArrayList in descending order, we can use the reverseOrder method of Collections class.
LinkedLists are better to use for the update operations whereas ArrayLists are better to use for the search operations. JavaTpoint offers too many high quality services. Mail us on hr javatpoint. Please mail your requirement at hr javatpoint.
Duration: 1 week to 2 week. All Interview. The main differences between the array and Collection are defined below: Arrays are always of fixed size, i. Arrays can only store homogeneous or similar type objects, but in Collection, heterogeneous objects can be stored. Arrays cannot provide the? List of interfaces of Collection Framework is given below: 1.
ArrayList; import java. Collection; import java. Collections; import java. Iterator; import java. Comparator; import java. Javatpoint Services JavaTpoint offers too many high quality services. ArrayList Vector 1. LinkedList takes more memory overhead, as it stores the object as well as the address of that object.
34 Java Collections Interview Questions
Here I am listing some important java collections interview questions and answers to help you in the interview. Collections are used in every programming language and initial java release contained few classes for collections: Vector , Stack , Hashtable , Array. But looking at the larger scope and usage, Java 1. Java Collections have come through a long way with the usage of Generics and Concurrent Collection classes for thread-safe operations. It also includes blocking interfaces and their implementations in java concurrent package.
These interview questions seems to be too common and appear in almost many interviews and that's the reason I never asked so called frequently asked or popular interview question, instead I ask something which is not so common like: 1 What is CopyOnWriteArrayList, how it is different than ArrayList and Vector? Generics, dynamic growing 7 What is BlockingQueue, how it is different than other collection classes flow control 8 How do you iterator over Synchronized HashMap, do you need to lock iteration and why? If anyone wants to answer this question , they must required a very good understanding of Java Collection framework which is whole purpose of these interview questions. By the way can you please share pdf version of your java collection interview for download? I think Collection interview questions listed here are very much appear in Capegemini or Tech Mahindra interview.
Looking for Java Collection job? Collections in Java is a group of objects to store and manipulate them. Please have a look at our Java Collection job interview questions and answers page to win your job. Question 1. What Is Java Collections Framework? Answer : Java Collections Framework provides a standard way to handle a group of objects.
Top 50 Core Java Interview Questions and Answers on Collections. In-depth guide with answers to wow the interviewer. Bonus: 20+ Videos & PDF interview.
[2020 Updated] Top 50 Java Collections Interview Questions and Answers
In this Collections Questions and Answers section you can learn and practice Collections Questions and Answers to improve your skills in order to face technical inerview conducted by organisations. By Practicing these interview questions, you can easily crack any Exams interview. Fully solved examples with detailed answer description.
Arrays are not dynamic. Once an array of a particular size is declared, the size cannot be modified. To add a new element to the array, a new array has to be created with bigger size and all the elements from the old array copied to new array.
Java Collections Interview Questions
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