More than 3000 questions in repository. There are more than 900 unanswered questions. Click here and help us by providing the answer. Have a video suggestion. Click Correct / Improve and please let us know.
Ans. Web Service promotes looser coupling but with comes with coding and performance overheads. Jars provide better performance and may be lesser coding but are problematic with update distribution. If the situation doesn't require frequent dependency updates and if it's only read operation of persistence, Having dependencies should be a better choice , otherwise web service.
Help us improve. Please let us know the company, where you were asked this question :
Ans. Fail fast systems are intolerant systems that fails at the first instance of smelling any problem. The objective here is to break the system instead of continuing with the possibly flawed processing. Example could be breaking the processing upon an exception.
Help us improve. Please let us know the company, where you were asked this question :
Ans. Fail Safe systems are tolerant systems that continue processing even if they sense any problem. the objective here is to continue with the processing even if there are some problems instead of completely shutting it down. Example could be to catch an exception and still letting it complete with partial results.
Help us improve. Please let us know the company, where you were asked this question :
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
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
Ans. Factory Pattern deals with creation of objects delegated to a separate factory class whereas Abstract Factory patterns works around a super-factory which creates other factories.
Help us improve. Please let us know the company, where you were asked this question :
Ans. Adapter object has a different input than the real subject whereas Proxy object has the same input as the real subject. Proxy object is such that it should be placed as it is in place of the real subject.
Help us improve. Please let us know the company, where you were asked this question :
Ans. The Difference between these patterns in only the intent. Adapter is used because the objects in current form cannot communicate where as in Facade , though the objects can communicate , A Facade object is placed between the client and subject to simplify the interface.
Help us improve. Please let us know the company, where you were asked this question :
Ans. Builder is a creational Design Pattern whereas Composite is a structural design pattern. Composite creates Parent - Child relations between your objects while Builder is used to create group of objects of predefined types.
Help us improve. Please let us know the company, where you were asked this question :
Ans. Factory is a creational design pattern whereas Strategy is behavioral design pattern. Factory revolves around the creation of object at runtime whereas Strategy or Policy revolves around the decision at runtime.
Help us improve. Please let us know the company, where you were asked this question :
Ans. In GUI programming, an object that can be registered to be notified when events of some given type occur. The object is said to listener? for the events.
Help us improve. Please let us know the company, where you were asked this question :
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
Help us improve. Please let us know the company, where you were asked this question :
Ans. It is part of the analysis of a program and describes a situation that a program might encounter and what behavior the program should exhibit in that circumstance.
Help us improve. Please let us know the company, where you were asked this question :
Ans. In First Case , Lock for the synchronized block will be received only if singleton == null whereas in second case every thread will acquire the lock before executing the code.
The problem of synchronization with singleton will only happen when the object has not be instantiated. Once instantiated , the check singleton == null will always generate true and the same object will be returned and hence no problem. First condition will make sure that synchronized access ( acquiring locks ) will only take place if the object has not been created so far.
Help us improve. Please let us know the company, where you were asked this question :
Which of the following is not the difference between Singleton and Static class ( Class with static members only ) ?
Only one object can be created for Singleton class whereas No objects are created for static class.
Singleton class instance is initiated using new keyword whereas static class instance is created using static method.
Singleton class can be serialized whereas Static class cannot be.
Singleton Class can participate in runtime Polymorphism whereas Static class cannot.
Very frequently asked. Usually followed by questions related to private constructor and synchronized access. Frequently asked in JPMorgan and TCS (Based on 2 feedback)
Q173. If you are given a choice to implement the code to either Insert a Record or Update if already exist, Which approach will you follow ?
1. Insert into the DB Table. If exception occurs, update the existing record. 2. Check if the record exists and update it if it exists, If not insert a new record.
Ans. In first case, there would be 2 DB calls in worst case and 1 in best case. In 2nd approach there will be always 2 DB calls.
Decision on the approach should depend on the following considerations -
1. How costly is the call to DB ? Are we using indices , hibernate etc
If calls to DB are costly , 1st approach should be the choice.
2. Exception Book keeping load upon exception.
The benefit of saving 1st call in approach 1 should be bigger than the Book keeping for the exception.
3. Probability of the exception in first apparoach.
If the DB Table is almost empty, it makes sense to follow Approach 1 as majority of the 1st calls will pass through without exception.
Help us improve. Please let us know the company, where you were asked this question :
LikeDiscussCorrect / Improve database insert-update db exceution plan db strategy design architecture technical lead
Q174. Shouldn't we make a class with all static members is its just expected to be executed as a standalone program with just one thread. Moreover Lets assume that there is no runtime Polymorphism required and there is no need for serialization ?
Ans. Still No in case we are making use of inheritance. we may have problem wherein we have program flow moving across common inherited method and specific methods of the derived class. call made to another static method in the parent class will only access the static class of the Parent class irrespective of the call from any of the derived class.
Help us improve. Please let us know the company, where you were asked this question :
Ans. We have multi tier architecture with multiple layers , We have series of web servers and applications in application tier, infrastructure libraries at middle tier and Database servers at the lower tier. We are using Oracle as Database, ESB ( Enterprise service Bus ) for asynchronous communication and Rest Web Services.
Help us improve. Please let us know the company, where you were asked this question :
LikeDiscussCorrect / Improve software system analyst development lead project lead technical lead technical architect
Very Frequently asked. Have been asked in HCL Technologies very frequently ( based on 3 feedback ). Among first few questions in many interviews.
Q178. Differences between abstract class and interface ?
Ans. Abstract classes can have both abstract methods ( method declarations ) as well as concrete methods ( inherited to the derived classes ) whereas Interfaces can only have abstract methods ( method declarations ).
A class can extend single abstract class whereas it can implement multiple interfaces.
Help us improve. Please let us know the company, where you were asked this question :
Q179. Which of the following is not the difference between Singleton and Static class ( Class with static members only ) ?
a. Only one object can be created for Singleton class whereas No objects are created for static class. b. Singleton class instance is initiated using new keyword whereas static class instance is created using static method. c. Singleton class can be serialized whereas Static class cannot be. d. Singleton Class can participate in runtime Polymorphism whereas Static class cannot.
Ans. Singleton class instance is initiated using new keyword whereas static class instance is created using static method.
Help us improve. Please let us know the company, where you were asked this question :
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.
Help us improve. Please let us know the company, where you were asked this question :
More than 3000 questions in repository.
Discuss 
Design Web Service vs Jar
Asked in 1 Companies
rare
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
Sample Code for equals
basic 
Try 6 Question(s) Test
Which of the following statement is not true ?
