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. ORM is the mapping technique, which maps object with relational data model. As we know that in java we need objects we can not user data in relational(in table form). So ORM is set of guideline which allows us to map relational data model in object form.
Help us improve. Please let us know the company, where you were asked this question :
Ans. There are four main OOP concepts in Java. These are:
Abstraction. Abstraction means using simple things to represent complexity. We all know how to turn the TV on, but we don?t need to know how it works in order to enjoy it. In Java, abstraction means simple things like objects, classes, and variables represent more complex underlying code and data. This is important because it lets avoid repeating the same work multiple times.
Encapsulation. This is the practice of keeping fields within a class private, then providing access to them via public methods. It?s a protective barrier that keeps the data and code safe within the class itself. This way, we can re-use objects like code components or variables without allowing open access to the data system-wide.
Inheritance. This is a special feature of Object Oriented Programming in Java. It lets programmers create new classes that share some of the attributes of existing classes. This lets us build on previous work without reinventing the wheel.
Polymorphism. This Java OOP concept lets programmers use the same word to mean different things in different contexts. One form of polymorphism in Java is method overloading. That?s when different meanings are implied by the code itself. The other form is method overriding. That?s when the different meanings are implied by the values of the supplied variables. See more on this below.
Help us improve. Please let us know the company, where you were asked this question :
Ans. Its is the process of creating exact copy of an object being cloned. In Object class one native method called clone() is there which is meant for Shallow Cloning of Object. Shallow cloning means bitwise copy of an object.In case of primitive data type it will create an exact copy of primitive values as well as variables but if the object contains any reference of an object then it will not copy the referenced object rather it will create the copy of reference variable and assigned it to the old object.
Help us improve. Please let us know the company, where you were asked this question :
Ans. The Java collections framework (JCF) is a set of classes and interfaces that implement commonly reusable collection data structures. Although referred to as a framework, it works in a manner of a library. The JCF provides both interfaces that define various collections and classes that implement them.
This question was recently asked at 'Bristlecone,Amazon Lab126,Amazon,Microsoft,Facebook,NCR,Google'.This question is still unanswered. Can you please provide an answer.
Help us improve. Please let us know the company, where you were asked this question :
Q287. Suppose we make an api call using multithreading, How would you design to make sure that we have received response for all threads before exiting the main thread ?
Ans. We can use HashMap for tracking response status for all threads. We can wait every n second by using Thread.sleep and exit the main thread only once we have received response for all threads.
Help us improve. Please let us know the company, where you were asked this question :
Ans. Unit Testing ( Junits )
Integration Testing ( Testing overall flow by calling the entry method or by calling the service end point )
Manual Testing ( End to End Manual User Testing, they way eventually it will be used by end users )
Automation Testing ( Machine replication of end to end testing )
Help us improve. Please let us know the company, where you were asked this question :
Ans. Every process in it's timeline require different resources. Utilization of resources can be optimized when they are shared among different processes or threads. When one thread is sleeping waiting for a peripheral to complete (e.g. a disk write, or a key press from the keyboard), other threads can continue using processor time and hence would lead to better usage of resources.
Help us improve. Please let us know the company, where you were asked this question :
Ans. 1. JVM that makes it platform independent and facilitates portability.
2. Garbage Collector that protects from Memory Leaks.
3. Only usage of references and not pointer arithmetic and hence protects the application from memory issues like dangling pointers, memory leaks etc.
4. Support for OOPs that makes application development and maintenance easy.
5. Facilitates library development through use of interface / abstract classes.
6. Facilitates creation of scalable applications.
7. Huge repository of libraries and pool of people with java skill.
Help us improve. Please let us know the company, where you were asked this question :
More than 3000 questions in repository.
Discuss 
ApplicationContext BeanFactory ApplicationContext vs BeanFactory 
frequent
Asked in 1 Companies 
Basic 
Frequently asked in Genpact.
Sample Code for Map
