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Interview Questions and Answers - Order By Newest | ||||
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Ans. Only declaring variables as final makes them immutable. Making objects final means that the object handler cannot be used to target some other object but the object is still mutable. | ||||
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Like Discuss Correct / Improve  java   oops   final   immutable  immutability   immutable  immutability object | ||||
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Ans. The properties class is a subclass of Hashtable that can be read from or written to a stream. | ||||
Sample Code for Load Properties using Property Class | ||||
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Like Discuss Correct / Improve  java   collections   hashtable   map   synchronization   synchronized | ||||
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Ans. member variable are loaded into heap, so they are initialized with default values when an instance of a class is created. In case of local variables, they are stored in stack until they are being used. | ||||
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Like Discuss Correct / Improve  java   jvm   memory management   variables   stack memory   heap memory   default values expert | ||||
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Ans. Externalizable interface is used to write the state of an object into a byte stream in compressed format. | ||||
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Like Discuss Correct / Improve  java   oops   serialization   externalizable interface   interface Asked in 3 Companies | ||||
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Ans. Serializable is a marker interface whereas externalizable is not. | ||||
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Like Discuss Correct / Improve  java   oops   serialization   externalizable   interface   marker interface | ||||
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Ans. No Abstract methods can only be declared protected or public. | ||||
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Like Discuss Correct / Improve  java   abstract   oops   access specifier   private   yes-no intermediate   rare | ||||
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Ans. Keep it as a Abstract Class if its a "Is a" Relationsship and should do subset/all of the functionality. Keep it as Interface if its a "Should Do" relationship. | ||||
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Like Discuss Correct / Improve  java   oops   abstract classes   interfaces   advanced Asked in 3 Companies | ||||
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Ans. Stands for Java API for XML Processing. This provides a common interface for creating and using SAX, DOM, and XSLT APIs in Java regardless of which vendor’s implementation is actually being used. | ||||
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Like Discuss Correct / Improve  java   java api   xml   xml processing   jaxp   abbreviation   technologies | ||||
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Ans. Stands for Java API for XML Binding. This standard defines a mechanism for writing out Java objects as XML and for creating Java objects from XML structures. | ||||
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Like Discuss Correct / Improve  java   xml   markup language   java api for xml binding   jaxb   abbreviation   technologies Asked in 2 Companies | ||||
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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Like Discuss Correct / Improve  java   java.util   comparable   comparator   collections Asked in 23 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. Since String is immutable, its hashcode is cached at the time of creation and it doesnt need to be calculated again. This makes it a great candidate for key in a Map and its processing is fast than other HashMap key objects. This is why String is mostly used Object as HashMap keys. | ||||
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Like Discuss Correct / Improve  java   string class   string   immutable  immutability   hashmap   immutable  immutability   hashcode   hash code   advanced Asked in 2 Companies expert   frequent | ||||
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Ans. public void checkIfAnagram(String str1,String str2){ boolean anagram = true; for(char c:str1.toCharArray()){ if(!str2.contains(String.valueOf(c))){ System.out.println("Strings are Anagrams"); anagram = false; } if(anagram == true){ System.out.println("Strings are not Anagrams"); } } } | ||||
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Like Discuss Correct / Improve   check if 2 strings are Anagrams Asked in 30 Companies basic   frequent | ||||
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Ans. These are the tables that are created temporarily and are deleted once the Stored Procedure is complete. For example - we may like to pull some info from a table and then do some operations on that data and then store the output in final output table. We can store the intermediary values in a temp table and once we have final output with us, we can just delete it. | ||||
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Like Discuss Correct / Improve  database   sql   temp tables   tables | ||||
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Ans. No, We cannot have duplicate keys in HashMap. If we attempt to do so , the previous value for the key is overwritten. | ||||
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Like Discuss Correct / Improve  java   collections   hashmap   map   hashtable | ||||
Try 1 Question(s) Test | ||||
Very frequently asked Hibernate interview question. Frequently asked in TCS ( based on 2 feedback ) | ||||
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Ans. There are 4 types of associations in Hibernate One to One One to Many Many to One Many to Many | ||||
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Like Discuss Correct / Improve  hibernate   associations Asked in 11 Companies   frequent | ||||
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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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Like Discuss Correct / Improve  java   oops concepts   abstraction   interfaces   abstract class   encapsulation  object oriented programming (oops)  oops concepts Asked in 3 Companies basic   frequent | ||||
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Ans. Stack memory areas is used to hold method and local variables while objects are always allocated memory in the heap. The heap memory is shared between multiple threads whereas Stack memory isn't. | ||||
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Like Discuss Correct / Improve  java   memory management   stack memory   heap memory   difference between   ebay Asked in 2 Companies intermediate   frequent | ||||
Try 1 Question(s) Test | ||||
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Ans. A trigger is a special kind of stored procedure that automatically gets executed upon an event in the database server. | ||||
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Like Discuss Correct / Improve  database   trigger Asked in 10 Companies basic   frequent | ||||
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Ans. The external tables feature is a complement to existing SQL Loader functionality. It enables to access data in external sources as if it were in a table in the database. We have used it few times for replicating tables across different database systems. | ||||
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Like Discuss Correct / Improve  external table oracle Asked in 1 Companies   rare | ||||
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Ans. When a Table Join itself , it's a Self Join. For example - we like to know the pair of department names where first dept has lesser employees than the later. Select D1.name , D2.name from Dept D1, Dept D2 where D1.employee_count < D2.employee_count | ||||
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Like Discuss Correct / Improve  sql  joins  self join  self-join  Pair of employee names with first having lesser salary than later  Pair of department names where first dept has lesser employees than the later Asked in 26 Companies basic   frequent | ||||
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Ans. int findMax(int[] items){ int maxNumber = 0; for(int x:items){ if(x > maxNumber){ maxNumber = x; } } return maxNumber; } | ||||
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Like Discuss Correct / Improve  coding  code  find max number in an array Asked in 1 Companies | ||||
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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. Selenium WebDriver is a tool for automating web application testing.It helps in replicating the manual tester behavior like keyboard entry, mouse events etc and then matching the output against the expected. | ||||
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Like Discuss Correct / Improve  selenium  webdriver Asked in 37 Companies | ||||
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Ans. Yes | ||||
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Like Discuss Correct / Improve  overloading  abstract methods  overloading abstract methods | ||||
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Ans. Strings are immutable in Java and not final. | ||||
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Like Discuss Correct / Improve  is string final  final  string  immutable  immutability  immutability | ||||
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Ans. Abstraction is a process of hiding the implementation details and describing only the functionality to the user. | ||||
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Like Discuss Correct / Improve  bstraction  oops concepts  oops principle Asked in 22 Companies | ||||
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Ans. LinkedList maintains the insertion order in collection. | ||||
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Like Discuss Correct / Improve  collections Asked in 1 Companies | ||||
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Ans. No | ||||
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Like Discuss Correct / Improve  abstract class   multiple inheritance  object oriented programming (oops)  oops concepts Asked in 2 Companies | ||||
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Ans. Unreachable code is a code segment that can never be executed in any case. For example - int x = 5; return; System.out.println(x); In this code , 2nd line will return the control out of the method and hence 3rd line will never get executed and hence is unreachable code. This will be caught at compile time only. | ||||
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Like Discuss Correct / Improve  unreachable code | ||||