Interview Questions and Answers for 'At' | Search Interview Question

Interview Questions and Answers - Order By Newest

Q151. serialization and deserialization of singleton class

Ans. The problem with serialized singleton class is that whenever we deserialize it, it will create a new instance of the class. To overcome this scenario all we need to do is to provide the implementation of readResolve() method.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve singleton serialization Asked in 1 Companies}

Q152. What is the cost of using Cloud Formation ?

Amazon Web Services (AWS)

Ans. Cloud Formation does not have any additional cost but you are charged for the underlying resources it builds.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve aws cloud formation}

Q153. Why is cloud infrastructure so powerful ?

Cloud Computing

Ans. Because it gives the ability to provision infrastructure on Demand with No contracts and strings attached.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve Amazon Web Service (AWS) Google Cloud Platform (GCP)}

Q154. What are the advantage of having Edge Locations ?

Amazon Web Services (AWS)

Ans. It saves Network traffic and facilitates faster delivery by hosting bulk media and cached data near to client.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve aws edge locations}

Q155. Which AWS services would you use if you have find a cheapest solution for an analytics application ?

Amazon Web Services (AWS)

Ans. Computation

Spot Price Plan
F1 or P3 Instance Type
Cold Hdd (SCI ) EBS Volume

Storage

S3-IA

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve aws computation aws ec2 aws computing amazon cloud computing amazon ec2}

Q156. What is JSON ?

Json

Ans. JSON is "JavaScript Object Notation", primarily used for client-server or server-server communication. Its a much lighter and readable alternative to XML. JSON is language independent and is easily parse-able in all programming languages.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve json markup language client server communication Asked in 26 Companies basic frequent}

Try 2 Question(s) Test

Q157. What is the role of JSON.stringify ?

Json

Ans. JSON.stringify() turns an object into a JSON text and stores that JSON text in a string.

So If we stringfy above notation , it will become

{"name":"xyz","gender":"male";"age":30}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve json JSON.stringify intermediate rare}

Q158. Which data types are supported by JSON ?

Json

Ans. Number
String
Boolean
Array
Object
null

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve json markup language client server communication}

Q159. Is tomcat an application or Web server ?

Server

Ans. Tomcat is a web server and a Servlet container. It is often used as an application server for web-based applications but does not include the complete suite of capabilities that a Java EE application server would supply.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve tomcat j2ee web server application server build management}

Q160. What are the default or implicitly assigned values for data types in java ?

Ans. boolean ---> false
byte ----> 0
short ----> 0
int -----> 0
long ------> 0l
char -----> /u0000
float ------> 0.0f
double ----> 0.0d
any object reference ----> null

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java data types default values}

Try 1 Question(s) Test

Q161. Can I import same package/class twice? Will the JVM load the package twice at runtime?

Core Java

Ans. One can import the same package or same class multiple times. Neither compiler nor JVM complains wil complain about it. And the JVM will internally load the class only once no matter how many times you import the same class.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java import jvm advanced Asked in 1 Companies intermediate rare}

Q162. What is meant by an "asynchronous event." Give some examples ?

Operating System

Ans. An asynchronous event is one that occurs at an unpredictable time outside the control of the program that the CPU is running. It is not "synchronized" with the program.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve j2ee internet web application asynchronus asynchronus communication architecture Asked in 1 Companies}

Q163. Give an Example of Annotations ?

Ans. Suppose that a software group traditionally starts the body of every class with comments providing important information:
public class Generation3List extends Generation2List {

// Author: John Doe
// Date: 3/17/2002
// Current revision: 6
// Last modified: 4/12/2004
// By: Jane Doe
// Reviewers: Alice, Bill, Cindy

// class code goes here

}
To add this same metadata with an annotation, you must first define the annotation type. The syntax for doing this is:
@interface ClassPreamble {
String author();
String date();
int currentRevision() default 1;
String lastModified() default "N/A";
String lastModifiedBy() default "N/A";
// Note use of array
String[] reviewers();
}
The annotation type definition looks similar to an interface definition where the keyword interface is preceded by the at sign (@) (@ = AT, as in annotation type). Annotation types are a form of interface, which will be covered in a later lesson. For the moment, you do not need to understand interfaces.
The body of the previous annotation definition contains annotation type element declarations, which look a lot like methods. Note that they can define optional default values.
After the annotation type is defined, you can use annotations of that type, with the values filled in, like this:
@ClassPreamble (
author = "John Doe",
date = "3/17/2002",
currentRevision = 6,
lastModified = "4/12/2004",
lastModifiedBy = "Jane Doe",
// Note array notation
reviewers = {"Alice", "Bob", "Cindy"}
)
public class Generation3List extends Generation2List {

// class code goes here

}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java annotations}

Q164. What are few of the Annotations pre defined by Java?

Ans. @Deprecated annotation indicates that the marked element is deprecated and should no longer be used. The compiler generates a warning whenever a program uses a method, class, or field with the @Deprecated annotation.

@Override annotation informs the compiler that the element is meant to override an element declared in a superclass.

@SuppressWarnings annotation tells the compiler to suppress specific warnings that it would otherwise generate.

@SafeVarargs annotation, when applied to a method or constructor, asserts that the code does not perform potentially unsafe operations on its varargsparameter. When this annotation type is used, unchecked warnings relating to varargs usage are suppressed.

@FunctionalInterface annotation, introduced in Java SE 8, indicates that the type declaration is intended to be a functional interface, as defined by the Java Language Specification.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java java8 annotations pre defined annotations}

Q165. What are meta Annotations ?

Ans. Annotations that apply to other annotations are called meta-annotations.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java annotations meta annotations}

Q166. Name few meta-annotations ?

Ans. @Retention annotation specifies how the marked annotation is stored:

@Documented annotation indicates that whenever the specified annotation is used those elements should be documented using the Javadoc tool. (By default, annotations are not included in Javadoc.)

@Target annotation marks another annotation to restrict what kind of Java elements the annotation can be applied to.

@Inherited annotation indicates that the annotation type can be inherited from the super class. (This is not true by default.) When the user queries the annotation type and the class has no annotation for this type, the class' superclass is queried for the annotation type. This annotation applies only to class declarations.

@Repeatable annotation, introduced in Java SE 8, indicates that the marked annotation can be applied more than once to the same declaration or type use. For more information, see Repeating Annotations.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java java8 annotations meta annotations}

Q167. How to display and set the Class path in Unix ?

Ans. To display the current CLASSPATH variable, use these commands in UNIX (Bourne shell):

% echo $CLASSPATH

To delete the current contents of the CLASSPATH variable,

In UNIX: % unset CLASSPATH; export CLASSPATH

To set the CLASSPATH variable,

In UNIX: % CLASSPATH=/home/george/java/classes; export CLASSPATH

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve unix unix commands classpath}

Very Frequently asked.Favorite question in Walk in drive for many Indian service companies.

Q168. What is a Final Class ?

Ans. A Class that cannot be sub classed.

Sample Code for final class

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java oops final final class java keyword basic interview question Asked in 3 Companies basic frequent}

Very frequently asked. Usually asked with questions related to String. Frequently asked at CTS / Cognizant

Q169. What is an Immutable Object ?

Core Java

Ans. Object that can't be changed after instantiation.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java oops immutable immutability Asked in 27 Companies basic frequent}

Try 2 Question(s) Test

Q170. Can we override static methods ? Why ?

Core Java

Ans. No.

Static methods belong to the class and not the objects. They belong to the class and hence doesn't fit properly for the polymorphic behavior.

A static method is not associated with any instance of a class so the concept of overriding for runtime polymorphism using static methods is not applicable.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java oops static static methods java keywords yes-no intermediate frequent}

Q171. How can we make sure that a code segment gets executed even in case of uncatched exceptions ?

Ans. By putting it within finally.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java oops exceptions finally uncatched exceptions basic frequent}

Q172. What is "super" used for ?

Ans. Used to access members of the base class.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java oops java keywords super basic interview question Asked in 2 Companies basic frequent}

Q173. Difference between Serialization and Deserialization ?

Core Java

Ans. Serialization is the process of writing the state of an object to a byte stream. Deserialization is the process of restoring these objects.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java oops serialization deserialization serialization vs deserialization Asked in 2 Companies basic frequent}

Try 1 Question(s) Test

Q174. What Design pattern Wrapper Classes implement ?

Design

Ans. Adapter.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java wrapper classes adapter design pattern design pattern}

Q175. Different types of memory used by JVM ?

Core Java

Ans. Class , Heap , Stack , Register , Native Method Stack.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java jvm memory management memory advanced architecture technical architect Asked in 1 Companies intermediate frequent}

Try 5 Question(s) Test

Q176. What is a Static import ?

Core Java

Ans. By static import , we can access the static members of a class directly without prefixing it with the class name.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java java5 static import static java keyword static import Asked in 4 Companies basic frequent}

Q177. What is a Property class ?

Core Java

Ans. The properties class is a subclass of Hashtable that can be read from or written to a stream.

Sample Code for Load Properties using Property Class

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java collections hashtable map synchronization synchronized}

Q178. Can we have multiple servlets in a web application and How can we do that ?

Java EE

Ans. Yes by making entries in web.xml

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve j2ee servlets servelets web application java web.xml yes-no architecture}

Q179. How can we manage Error Messages in the web application ?

Solution

Ans. Within message.properties file.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve j2ee web application struts spring Asked in 1 Companies}

Q180. Difference between Proxy and Adapter ?

Design

Ans. Adapter object has a different input than the real subject whereas Proxy object has the same input as the real subject. Proxy object is such that it should be placed as it is in place of the real subject.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java design pattern proxy adapter proxy vs adapter expert}

Search Interview Questions

Help us and Others Improve. Please let us know the questions asked in any of your previous interview.