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

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Q61. What are the contents of Hibernate configuration file ( hibernate.cfg.xml ) ?

Ans. HBM Files ( Mapping )
DB Connection ( DB Connection String , User Name , Password , Pool Size )
SQL Dialect ( SQL variant to be generated )
Show SQL ( Show / No show SQL on Console )
Auto Commit ( True / False )

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Q62. Difference beween HashSet and TreeSet ?

Core Java

Ans. 1. HashSet doesnt maintain its elements in any specific order and is all random whereas TreeSet maintains elements in natural order 9 order defined by the equals method of TreeSet element type )

2. TreeSet doesnt allow null elements whereas HashMap does.

3. As TreeSet orders elements and is hence insertion is comparatively slower.

4. HashSet performs basic operations like add(), remove(), contains(), size() etc. in a constant size time. A TreeSet performs these operations at the order of log(n) time.

5. HashMap in Java internally backs a HashSet. A NavigableMap backs a TreeSet internally.

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Q63. Which elements of a class are ignored during serialization ?

Core Java

Ans. 1. Objects are serialized and not classes and hence Static variables are ignored.

2. Transient is an explicit declaration to ignore the variable during serialization and hence transient instance variables are ignored too.

3. Base class instance variables if the base class hasn't been declared serializable.

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Q64. What are the different Route53 routing policies ?

Amazon Web Services (AWS)

Ans. Simple
Weighted
Latency
Failover
GeoLocation
Multivalue

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Q65. What is a cookie ?

Java EE

Ans. A cookie is a small piece of text stored on a user's computer by the browser for a specific domain. Commonly used for authentication, storing site preferences, and server session identification.

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Q66. What are the different types of inner classes ?

Core Java

Ans. Simple Inner Class,
Local Inner Class,
Anonymous Inner Class,
Static Nested Inner Class.

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Frequently asked in Indian Service Companies. Tech Mahindra ( Based on 3 inputs ) and Infosys ( 3 inputs )

Q67. What is the difference between List, Set and Map ?

or

What are the different Java Collections Interfaces ?

Core Java

Ans. List - Members are stored in sequence in memory and can be accessed through index.
Set - There is no relevance of sequence and index. Sets doesn't contain duplicates whereas multiset can have duplicates.
Map - Contains Key , Value pairs.

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Frequently asked at HCL Technologies ( Based on 3 feedback )

Q68. Difference between Checked and Unchecked exceptions ?

Core Java

Ans. Checked exceptions are the exceptions for which compiler throws an errors if they are not checked whereas unchecked exceptions are caught during run time only and hence can't be checked.

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Very frequently asked. Favorite question in Walk in Drive of many Indian service companies.

Q69. What is a Final Variable ?

Core Java

Ans. Final variable is a variable constant that cannot be changed after initialization.

Sample Code for final variable

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Q70. Difference between Vector and ArrayList ?

Core Java

Ans. Vectors are synchronized whereas Array lists are not.

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Very Frequently asked. Usually asked along with String Class related questions.

Q71. What is an immutable class ?

Core Java

Ans. Class using which only immutable (objects that cannot be changed after initialization) objects can be created.

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Very frequently asked in phone and walk in interviews.

Q72. What are Marker Interfaces ? Name few Java marker interfaces ?

Core Java

Ans. An interface without any method declaration is called as marker interface. there are 3 in-built interfaces in JVM i.e. serializable, clonable, remote

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Very frequently asked. Usually difference between String,StringBuffer and StringBuilder is asked in different variations.

Q73. Difference between StringBuffer and StringBuilder ?

Core Java

Ans. StringBuffer is synchronized whereas StringBuilder is not.

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Q74. What is reflection ?

Ans. It is the process of examining / modifying the behaviour of an object at runtime.

Sample Code for reflection

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Q75. When do you get ClassCastException?

or

What is ClassCastException ?

Ans. As we only downcast class in the hierarchy, The ClassCastException is thrown to indicate that code has attempted to cast an object to a subclass of which it is not an instance.

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Q76. What is constructor chaining and how is it achieved in Java?

Core Java

Ans. A child object constructor always first needs to construct its parent. In Java it is done via an implicit call to the no-args constructor as the first statement

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Very Frequently asked.

Q77. Explain throw, throws , try and catch in Java ?

Core Java

Ans. throw is used to re throw an exception.throws is used to declare that the method throws the respective exceptions.try block is used to identify if the respective block has thrown any exception.catch is used to catch the exception that has been thrown by the respective try block.

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Q78. Difference between jar , war and ear ?

Java EE

Ans. Jar is Java Archieve i.e compressed Class or Class / Java files.

War comprises of compressed Servlet class files,JSP FIles,supporting files, GIF and HTML files.

Ear comprise of compressed Java and web module files ( was files ).

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Q79. What is a BlockingQueue?

Data Structures

Ans. BlockingQueue is a Queue that supports operations that wait for the queue to become non-empty when retrieving and removing an element, and wait for space to become available in the queue when adding an element.

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Q80. Difference between GET and POST Requests ?

Web Service

Ans. GET is supposed to get information from the server. Client sends the minimal information so that Server can respond with the response body on basis of request. For example - You want to get complete employment record for employee id 123

POST is supposed to send the information for submission. Payload or a Body is usually sent so that it can be persisted on the server. For example - Sending the complete information of an employee ( id, name , dept etc ) to the server for persisting it.

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Q81. What is coupling and Cohesion ?

Design

Ans. Coupling is the degree of interdependence between software modules, a measure of how closely connected two modules are or the strength of the relationships between modules.

Cohesion refers to the degree to which the elements of a module belong together. Cohesion measures the strength of relationship between pieces of functionality within a given module.

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Q82. Write a Program to reverse a Linked List ?

Data Structure

^{This question was recently asked at 'Myntra,Compro Technologies'.This question is still unanswered. Can you please provide an answer.}

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Q83. Why java doesn't support multiple Inheritance ?

or

Explain Java Diamond Problem.

Core Java

Ans. class A {
void test() {
System.out.println("test() method");
}
}

class B {
void test() {
System.out.println("test() method");
}
}

Suppose if Java allows multiple inheritance like this,

class C extends A, B {
}

A and B test() methods are inheriting to C class.

So which test() method C class will take? As A & B class test() methods are different , So here we would Facing Ambiguity.

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Usually asked to entry level software developers.

Q84. Write a program to swap two variables without using third

Core Java

Ans. public static void main(String[] args) {
   int num1 = 1;
   int num2 = 2;
   num1 = num1^num2;
   num2 = num1^num2;
   num1 = num1^num2;
   System.out.print("num1 = " + num1 +", num2 = "+num2);
}

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Q85. What is the difference between Singleton and Prototype Bean scope in Spring ?

Spring

Ans. Prototype scope - A new object is created each time it is injected/looked up. It will use new SomeClass() each time.

Singleton scope - It is the default scope. The same object is returned each time it is injected/looked up. Here it will instantiate one instance of SomeClass and then return it each time.

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Q86. What are the problems one could face while working with serverless technologies like AWS Lambda ?

Amazon Web Services (AWS)

Ans. Warm up time for certain technologies like Java ( JVM Warmup )

Performance

Size of Deployable ( Bigger size packaging should go in S3 )

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Q87. 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.

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

Q88. What is a Final Class ?

Ans. A Class that cannot be sub classed.

Sample Code for final class

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

Q89. What is an Immutable Object ?

Core Java

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

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Q90. 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.

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