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Core java - Interview Questions and Answers for 'Mphasis' - 14 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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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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Basic and Very Frequently asked. | ||||
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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. | ||||
Sample Code for overloading Sample Code for overriding | ||||
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Like Discuss Correct / Improve  polymorphism  object oriented programming (oops)  oops concepts  oops concepts Asked in 108 Companies Basic   frequent | ||||
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Frequently asked in Infosys India | ||||
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Ans. String pool (String intern pool) is a special storage area in Java heap. When a string is created and if the string already exists in the pool, the reference of the existing string will be returned, instead of creating a new object and returning its reference. | ||||
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Like Discuss Correct / Improve  java   oops   string   string class   string pool   heap memory Asked in 31 Companies intermediate   frequent | ||||
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Advanced level question usually asked in High end product companies. Have been asked in Google and Amazon (Based on 1 Feedback) | ||||
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Ans. The Java runtime environment deletes objects when it determines that they are no longer being used. This process is known as garbage collection. The Java runtime environment supports a garbage collector that periodically frees the memory used by objects that are no longer needed. The Java garbage collector is a mark-sweep garbage collector that scans Java dynamic memory areas for objects, marking those that are referenced. After all possible paths to objects are investigated, those objects that are not marked (i.e. are not referenced) are known to be garbage and are collected. | ||||
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Like Discuss Correct / Improve  java   garbage collection   java memory management   advanced Asked in 21 Companies intermediate   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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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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Like Discuss Correct / Improve  java   oops   final   final method Asked in 30 Companies basic   frequent | ||||
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Ans. JDK(Java Development kit) = Development Kit comprising of JVM , library and development tools for developers JRE (Java Run time Environment) - Comprise of JVM and set of libraries JVM(Java Virtual Machine) = Interpreter which reads the .class file line by line. When we install JDK, JRE also get installed so we can write,compile and excute our code. Used by developer. Without JDK we can only execute the program using JRE. | ||||
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Ans. It in Java is used to indicate that a field should not be serialized. | ||||
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Like Discuss Correct / Improve  java   oops   serialization   transient   java keywords Asked in 39 Companies intermediate   frequent | ||||
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Ans. Collections class is a utility class having static methods for doing operations on objects of classes which implement the Collection interface. For example, Collections has methods for finding the max element in a Collection. | ||||
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Like Discuss Correct / Improve  java   collections   collections class   collection interface   basic interview question Asked in 6 Companies basic   frequent | ||||
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Ans. Externalizable is an interface which contains two methods readExternal and writeExternal. These methods give you a control over the serialization mechanism. | ||||
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Like Discuss Correct / Improve  java   serialization   externalizable interface Asked in 2 Companies intermediate   rare | ||||
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Ans. Abstraction, Encapsulation, Polymorphism , Composition and Inheritance | ||||
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Like Discuss Correct / Improve  core oops concepts Asked in 65 Companies basic   frequent | ||||
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Ans. String[] s = { "sort", "string", "array" }; Collections.sort(Arrays.asList(s)); System.out.println(Arrays.toString(s)); // [array, sort, string] | ||||
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