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Interview Questions and Answers for 'SAP' - 25 question(s) found - Order By Newest | ||||
Very frequently asked. Among first few questions in almost all interviews. Among Top 5 frequently asked questions. Frequently asked in Indian service companies (HCL,TCS,Infosys,Capgemini etc based on multiple feedback ) and Epam Systems | ||||
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Ans. "equals" is the method of object class which is supposed to be overridden to check object equality, whereas "==" operator evaluate to see if the object handlers on the left and right are pointing to the same object in memory. x.equals(y) means the references x and y are holding objects that are equal. x==y means that the references x and y have same object. Sample code: String x = new String("str"); String y = new String("str"); System.out.println(x == y); // prints false System.out.println(x.equals(y)); // prints true | ||||
Sample Code for equals | ||||
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Like Discuss Correct / Improve  java   string comparison   string   object class   ==   equals   object equality  operator   == vs equals   equals vs == Asked in 294 Companies basic   frequent | ||||
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Advanced level question. Frequently asked in High end product companies. Frequently asked in Google , Cognizant and Deloitte ( Based on 2 feedback ) | ||||
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Ans. 1. String Pool - When a string is created and if it exists in the pool, the reference of the existing string will be returned instead of creating a new object. If string is not immutable, changing the string with one reference will lead to the wrong value for the other references. Example - String str1 = "String1"; String str2 = "String1"; // It doesn't create a new String and rather reuses the string literal from pool // Now both str1 and str2 pointing to same string object in pool, changing str1 will change it for str2 too 2. To Cache its Hashcode - If string is not immutable, One can change its hashcode and hence it's not fit to be cached. 3. Security - String is widely used as parameter for many java classes, e.g. network connection, opening files, etc. Making it mutable might possess threats due to interception by the other code segment. | ||||
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Like Discuss Correct / Improve  java   oops   string   string class   immutable  immutability   advanced Asked in 39 Companies expert   frequent | ||||
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Ans. OOPs or Object Oriented Programming is a Programming model which is organized around Objects instead of processes. Instead of a process calling series of processes, this model stresses on communication between objects. Objects that all self sustained, provide security by encapsulating it's members and providing abstracted interfaces over the functions it performs. OOP's facilitate the following features 1. Inheritance for Code Reuse 2. Abstraction for modularity, maintenance and agility 3. Encapsulation for security and protection 4. Polymorphism for flexibility and interfacing | ||||
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Like Discuss Correct / Improve  oops  oops features Asked in 260 Companies basic   frequent | ||||
Frequently asked at Manhattan Associates ( Based on 2 feedback ) | ||||
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Ans. Its an anonymous method without any declaration. Lambda Expression are useful to write shorthand Code and hence saves the effort of writing lengthy Code. It promotes Developer productivity, Better Readable and Reliable code. | ||||
Sample Code for lambda | ||||
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Like Discuss Correct / Improve  java   java8   lambda expression   architecture Asked in 58 Companies expert   frequent | ||||
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Frequently asked question in companies using Hibernate. | ||||
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Ans. It's a feature to lazily initialize dependencies , relationship and associations from the Database. Any related references marked as @OneToMany or @ManyToMany are loaded lazily i.e when they are accessed and not when the parent is loaded. | ||||
Sample Code for Lazy Initialization | ||||
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Like Discuss Correct / Improve  hibernate   lazy loading hibernate   lazy initialization hibernate   architecture Asked in 77 Companies Basic   frequent | ||||
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Ans. abstract and final | ||||
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Like Discuss Correct / Improve  java   java keywords Asked in 2 Companies basic | ||||
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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Like Discuss Correct / Improve  java   oops   overloading   overriding   oops concepts   basic interview question   overloading vs overriding Asked in 86 Companies basic   frequent | ||||
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Frequently asked in Cognizant (CTS) | ||||
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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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Like Discuss Correct / Improve  java   oops   serialization Asked in 18 Companies basic   frequent | ||||
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Ans. We can overload the main method by specifying different argument types. For example - 2 main methods with different arguments is perfectly legal public static void main(); public static void main(String[] args); The following are not legal as compiler will complain of duplicate methods public static void main(String[] args); public static void main(String[] args); Even The following are not legal as we cannot overload on return types public static String main(String[] args); public static void main(String[] args); | ||||
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Like Discuss Correct / Improve  main method Asked in 2 Companies | ||||
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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Like Discuss Correct / Improve  java   exceptions   checked exceptions   unchecked exceptions   exception handling   checked vs unchecked exceptions Asked in 39 Companies basic   frequent | ||||
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Ans. Generalization or UpCasting is a phenomenon where a sub class is prompted to a super class, and hence becomes more general. Generalization needs widening or up-casting. Specialization or DownCasting is a phenomenon where a super class is narrowed down to a sub class. Specialization needs narrowing or down-casting. | ||||
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Like Discuss Correct / Improve  java   data types   casting  type casting   up casting  type casting   downcasting  type casting   generalization   specialization Asked in 2 Companies | ||||
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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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Like Discuss Correct / Improve  blockingqueue   collections   java   concurrent collections Asked in 10 Companies | ||||
Usually asked to entry level software developers. | ||||
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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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Like Discuss Correct / Improve  code  coding Asked in 37 Companies basic   frequent | ||||
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Ans. The memory pool containing all the reflective data of the java virtual machine itself, such as class and method objects. With Java VMs that use class data sharing, this generation is divided into read-only and read-write areas. The Permanent generation contains metadata required by the JVM to describe the classes and methods used in the application. The permanent generation is populated by the JVM at runtime based on classes in use by the application. In addition, Java SE library classes and methods may be stored here. | ||||
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Like Discuss Correct / Improve  java   jvm   memory management   permgen   permanent generation   advanced   architecture Asked in 9 Companies expert | ||||
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Ans. https://en.wikipedia.org/wiki/Database_normalization | ||||
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Like Discuss Correct / Improve  normalization  database Asked in 35 Companies intermediate   frequent | ||||
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Ans. ClassNotFoundException is checked exception whereas NoClassDefFoundError is a unchecked exception. | ||||
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Like Discuss Correct / Improve  java   exceptions   checked exceptions   unchecked exceptions   exception handling Asked in 2 Companies | ||||
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Ans. No. Enums are final by design. | ||||
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Like Discuss Correct / Improve  java   enums   inheritance  object oriented programming (oops)  oops concepts   yes-no Asked in 1 Companies intermediate | ||||
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Ans. Abstract means that the class is only meant to be subclassed whereas final means that it cannot be subclassed so both concepts - abstract and final are actually mutually exclusive and hence not permitted together. | ||||
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Ans. Audit Tables generally stores Raw information to be reviewed in case of problems or determining impact. If Database space is an issue , and the audit information is rarely retrieved, one design could be to use compressed file system. | ||||
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Like Discuss Correct / Improve  databases   audit tables   raw transaction information storage Asked in 1 Companies | ||||
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Ans. Enums in Java are used to declare predefined objects and then reuse them. they offer many benefits 1. Enum instance are type safe and thread safe. 2. Enum instances are singleton and hence reused. 3. If we use Enums with Switch , It makes sure that the passed argument is either of its instance and hence provides a safeguard. 4. If we use Enum with Sorted Collections we can sort the elements with a predefined priorities ( as per constant declaration in enum ) 5. We can use Enum as a Factory by defining its constructor. 6. We can store related constant data within enum. For example - If we know the values for the map upfront, we can alternatively use an enum. | ||||
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Ans. This scope indicates that the dependency is not required for normal use of the application, and is only available for the test compilation and execution phases. This scope is not transitive. | ||||
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Ans. A dirty read occurs when a transaction is allowed to read data from a row that has been modified by another running transaction but not yet committed. | ||||
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Like Discuss Correct / Improve  database transaction Asked in 8 Companies | ||||
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Ans. Factory Design Patterns is the pattern that recommends creation of separate Factory Object for creation of other object. So its like saying - If you want to create an object of ClassA, Talk to FactoryObject ( which is an object of FactoryClass ). FactoryObject in itself encapsulates the inputs and logic required to make the decision regarding the creation and construction of object. | ||||
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Like Discuss Correct / Improve  design pattern  factory design pattern Asked in 9 Companies | ||||
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Ans. Yes we can have a main method with string[] argument in every class of an application. When we execute an app we specify the starting point i.e the class that will get the control first and hence main method of that class gets executed. | ||||
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Like Discuss Correct / Improve  main method Asked in 3 Companies | ||||
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Ans. Every fresh session having its own cache memory, Caching is a mechanism for storing the loaded objects into cache memory. The advantage of cache mechanism is, whenever again we want to load the same object from the database then instead of hitting the database once again, it loads from the local cache memory only, so that the no. of round trips between an application and a database server got decreased. It means caching mechanism increases the performance of the application. In hibernate we have two levels of caching First Level Cache [ or ] Session Cache Second Level Cache [ or ] Session Factory Cache [ or ] JVM Level Cache | ||||
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Like Discuss Correct / Improve   Asked in 23 Companies | ||||