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Interview Questions and Answers - Order By Newest | ||||
Recently asked in TCS , Tech Mahindra, HCL , Accenture and Fidelity. | ||||
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Ans. The DispatcherServlet configured in web.xml file receives the request. The DispatcherServlet finds the appropriate Controller with the help of HandlerMapping and then invokes associated Controller. Then the Controller executes the logic business logic and then returns ModeAndView object to the DispatcherServlet. The DispatcherServlet determines the view from the ModelAndView object. Then the DispatcherServlet passes the model object to the View. The View is rendered and the Dispatcher Servlet sends the output to the Servlet container. Finally Servlet Container sends the result back to the user. | ||||
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Like Discuss Correct / Improve  j2ee   spring   mvc   frameworks   web applications   architecture Asked in 11 Companies Basic   frequent | ||||
Very Frequently asked to fresh graduates and less experienced. Favorite question in Walk in drives. Frequently asked in Indian Services companies. | ||||
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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. | ||||
Sample Code for overloading Sample Code for overriding | ||||
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Very frequently asked across all types of companies. | ||||
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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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Frequently asked in Cognizant ( Based on 2 feedback ) | ||||
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Ans. Inner join is the intersection of two tables on the condition defined by the where clause i.e will get records from both tables matched by a column. Outer join is the union of two tables i.e will get all records from both tables and will put null in the columns where related records are not present. Left Outer join is the left union of two tables i.e all records from the table on the left and values from the right table for related records else null for the columns from right table. Right Outer join is the right union of two tables i.e all records from the table on the right and values from the left table for related records else null for the columns from left table. | ||||
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Very frequently asked. Favorite question in Walk in Drive of many Indian service companies. | ||||
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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. There are two types of casting, casting between primitive numeric types and casting between object references. Casting between numeric types is used to convert larger values, such as double values, to smaller values, such as byte values. Casting between object references is used to refer to an object by a compatible class, interface, or array type reference | ||||
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Very frequently asked. Favorite question in Walk in Drive of many Indian service companies. | ||||
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Ans. They are different the way their elements are stored in memory. TreeMap stores the Keys in order whereas HashMap stores the key value pairs randomly. | ||||
Sample Code for treemap Sample Code for hashmap | ||||
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Almost sure to be asked in every company using any Dependency Injection framework ( Spring, Guice etc ) | ||||
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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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Very Frequently asked across all type of companies and across all levels. | ||||
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Ans. Private - Not accessible outside object scope. Public - Accessible from anywhere. Default - Accessible from anywhere within same package. Protected - Accessible from object and the sub class objects. | ||||
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Advanced level question. Recently asked in few Indian service companies ( Based on 3 inputs ) | ||||
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Ans. Bootstrap - Loads JDK internal classes, java.* packages. Extensions - Loads jar files from JDK extensions directory - usually lib/ext directory of the JRE System - Loads classes from system classpath. | ||||
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Very frequently asked.Usually among first few questions. | ||||
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Ans. MVC is a Design Pattern that facilititates loose coupling by segregating responsibilities in a Web application 1. Controller receives the requests and handles overall control of the request 2. Model holds majority of the Business logic, and 3. View comprise of the view objects and GUI component | ||||
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Frequently asked to fresh graduates and less experienced. | ||||
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Ans. Inheritance means a object inheriting reusable properties of the base class. Compositions means that an abject holds other objects. In Inheritance there is only one object in memory ( derived object ) whereas in Composition , parent object holds references of all composed objects. From Design perspective - Inheritance is "is a" relationship among objects whereas Composition is "has a" relationship among objects. | ||||
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Ans. public or default | ||||
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Very frequently asked. Usually asked in different variants like Diff between StringBuffer , String Builder ; Difference between StringBuilder and String class; Choice between these classes etc. | ||||
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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. A Stream is an abstraction that either produces or consumes information. There are two types of Streams : Byte Streams: Provide a convenient means for handling input and output of bytes. Character Streams: Provide a convenient means for handling input & output of characters. Byte Streams classes: Are defined by using two abstract classes, namely InputStream and OutputStream. Character Streams classes: Are defined by using two abstract classes, namely Reader and Writer. | ||||
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Frequently asked at HCL Technologies ( Based on 3 feedback ) | ||||
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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. | ||||
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Ans. Final variable is a variable constant that cannot be changed after initialization. | ||||
Sample Code for final variable | ||||
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Ans. Vectors are synchronized whereas Array lists are not. | ||||
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Ans. It in Java is used to indicate that a field should not be serialized. | ||||
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Very Frequently asked. Usually asked along with String Class related questions. | ||||
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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. | ||||
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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. | ||||
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Ans. StringBuffer is synchronized whereas StringBuilder is not. | ||||
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Ans. It is the process of examining / modifying the behaviour of an object at runtime. | ||||
Sample Code for reflection | ||||
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Ans. It should be followed by either catch or finally block. | ||||
Sample Code for Retry in case of exception | ||||
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Frequently asked in CTS ( Based on 2 feedback ) | ||||
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Ans. Comparable interface is used for single sequence sorting i.e.sorting the objects based on single data member where as comparator interface is used to sort the object based on multiple data members. | ||||
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Ans. Collections are re-sizable in nature. We can increase or decrease the size as per recruitment. Collections can hold both homogeneous and heterogeneous data's. Every collection follows some standard data structures. Collection provides many useful built in methods for traversing,sorting and search. | ||||
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Ans. Abstraction is provided in Java by following ways - Coding to the ( Interfaces / Abstract Classes ) or contracts By Encapsulating details within classes and exposing the minimal Door ( few public methods ) | ||||
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Ans. DEBUG ERROR ALL WARN INFO FATAL OFF TRACE TRACE_INT WARN | ||||
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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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Ans. Java only provides pass by value. | ||||
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