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Interview Questions and Answers for 'Infosys technologies' - 23 question(s) found - Order By Newest | ||||
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Ans. 1.Abstraction solves the problem at design level while encapsulation solves the problem at implementation level 2.Abstraction is used for hiding the unwanted data and giving relevant data. while Encapsulation means hiding the code and data into a single unit to protect the data from outside world. 3. Abstraction lets you focus on what the object does instead of how it does it while Encapsulation means hiding the internal details or mechanics of how an object does something. 4.For example: Outer Look of a Television, like it has a display screen and channel buttons to change channel it explains Abstraction but Inner Implementation detail of a Television how CRT and Display Screen are connect with each other using different circuits , it explains Encapsulation. | ||||
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Ans. Polymorphism means the condition of occurring in several different forms. Polymorphism in Java is achieved in two manners 1. Static polymorphism is the polymorphic resolution identified at compile time and is achieved through function overloading whereas 2. Dynamic polymorphism is the polymorphic resolution identified at runtime and is achieved through method overriding. | ||||
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Ans. Overloading - Similar Signature but different definition , like function overloading. Overriding - Overriding the Definition of base class in the derived class. | ||||
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Ans. Storing the state of an object in a file or other medium is called serialization. Classes can communicate only if they are built together ( as they need Byte code for communication ). What if we need to enable communication between different applications ( i.e they have been built independently or even they reside at different locations ), We need a mechanism that will transfer the Bean state to a Medium than can be transferred to the receiving application. | ||||
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Ans. Hashtable is synchronized whereas HashMap is not.HashMap allows null values whereas Hashtable doesnt allow null values. | ||||
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Ans. Its a method which cannot be overridden. Compiler throws an error if we try to override a method which has been declared final in the parent class. | ||||
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Ans. It is a Design Pattern that facilitates loose coupling by sending the dependency information ( object references of dependent object ) while building the state of the object. Objects are designed in a manner where they receive instances of the objects from other pieces of code, instead of constructing them internally and hence provide better flexibility. | ||||
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Ans. A string buffer implements a mutable sequence of characters. A string buffer is like a String, but can be modified. At any point in time it contains some particular sequence of characters, but the length and content of the sequence can be changed through certain method calls. The String class represents character strings. All string literals in Java programs, such as "abc" are constant and implemented as instances of this class; their values cannot be changed after they are created. | ||||
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Ans. StringBuffer is synchronized whereas StringBuilder is not. | ||||
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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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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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Ans. With Java 8, We can provide method definitions in the Interfaces that gets carried down the classes implementing that interface in case they are not overridden by the Class. Keyword "default" is used to mark the default method. | ||||
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Ans. [Open Ended Answer] | ||||
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Ans. No | ||||
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Ans. WEB APP |WEB-INF - META-INF | | | META-INF.MF | lib - WEB.xml - Classes | ||||
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Ans. Destructor is used to de-allocate memory allocated by objects. There are no destructors in Java. Alternatively, Java provides Automatic garbage collection i.e automatically releasing the un-referenced memory. | ||||
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Ans. Generics are a facility of generic programming that were added to the Java programming language in 2004 within J2SE5.0. They allow "a type or method to operate on objects of various types while providing compile-time type safety. | ||||
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Ans. There are four main OOP concepts in Java. These are: Abstraction. Abstraction means using simple things to represent complexity. We all know how to turn the TV on, but we don?t need to know how it works in order to enjoy it. In Java, abstraction means simple things like objects, classes, and variables represent more complex underlying code and data. This is important because it lets avoid repeating the same work multiple times. Encapsulation. This is the practice of keeping fields within a class private, then providing access to them via public methods. It?s a protective barrier that keeps the data and code safe within the class itself. This way, we can re-use objects like code components or variables without allowing open access to the data system-wide. Inheritance. This is a special feature of Object Oriented Programming in Java. It lets programmers create new classes that share some of the attributes of existing classes. This lets us build on previous work without reinventing the wheel. Polymorphism. This Java OOP concept lets programmers use the same word to mean different things in different contexts. One form of polymorphism in Java is method overloading. That?s when different meanings are implied by the code itself. The other form is method overriding. That?s when the different meanings are implied by the values of the supplied variables. See more on this below. | ||||
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Ans. Possible Answer - Java Developer | ||||
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Ans. The most effective and acceptable reasons for leaving your current job should be positive e.g. moving forward in your life or career | ||||
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Ans. The garbage collection is a facility wherein a program runs on the Java Virtual Machine which gets rid of objects, which are not being used by a Java application anymore. It is a form of automatic memory management and recollection. | ||||
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Ans. [Open Ended Answer] Possible Answer - We are using Agile. We have daily standups, Bi weekly Backlog Grooming , Planning and Retrospective, We have a 2 week sprint and We use Jira for Scrum Management. We are using Java 8, Spring Boot, JSF , Apache Kafka , Soap as well as Rest Services. | ||||
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Ans. Assigning a value of one type to a variable of another type is known as Type Casting. Example : int x = 10; byte y = (byte)x; In Java, type casting is classified into two types, Widening Casting(Implicit) widening-type-conversion and Narrowing Casting (Explicitly done) narrowing-type-conversion. Widening or Automatic type converion - Automatic Type casting take place when,the two types are compatible and the target type is larger than the source type Example : public class Test { public static void main(String[] args) { int i = 100; long l = i; //no explicit type casting required float f = l;//no explicit type casting required System.out.println("Int value " i); System.out.println("Long value " l); System.out.println("Float value " f); } } Narrowing or Explicit type conversion - When you are assigning a larger type value to a variable of smaller type, then you need to perform explicit type casting. Example : public class Test{ public static void main(String[] args) { double d = 100.04; long l = (long)d; //explicit type casting required int i = (int)l;//explicit type casting required System.out.println("Double value " d); System.out.println("Long value " l); System.out.println("Int value " i); } } | ||||
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