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| Ans. Criteria is a simplified API for retrieving entities by composing Criterion objects. For example - session.createCriteria(Employee.class).add( Restrictions.like("name", "A%") ).list(); will return all employee objects having name starting with A. | ||||
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| Ans. JIRA is written in Java and uses the Pico IOC container,Apache OFBiz entity engine, and WebWork technology stack. For remote procedure calls (RPC), JIRA supports REST, SOAP, and XML RPC. | ||||
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| Ans. Collision is the situation when two different elements have the same Hash Code. | ||||
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| Ans. We are using cluster of Web servers and Application servers. Load Balancer is used to manage the load between them. Down the layer we have middleware server and then DB server to access database. | ||||
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| Ans. Its a facility for code reuse and independent extension wherein a derived class inherits the properties of parent class. | ||||
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| Ans. PUT requests are only meant to place the object as it is on server. For example - You want a file to be uploaded and then placed in a particular folder or you want an Employee object to be persisted in the table. POST requests are also meant to transfer information from client to server but that information once received at the server is evaluated , modified or refactored before persisting. | ||||
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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. The prototype pattern is a creational design pattern. It is used when the type of objects to create is determined by a prototypical instance, which is cloned to produce new objects. Prototype is used when we need duplicate copies of objects. | ||||
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| Ans. A Web service is a service offered by one system to another, for communication over web through http. XML are JSON are usually used for sending across information from one system to another. | ||||
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| Ans. <a href="http://javahungry.blogspot.com/2015/03/difference-between-array-and-arraylist-in-java-example.html" rel="nofollow">http://javahungry.blogspot.com/2015/03/difference-between-array-and-arraylist-in-java-example.html</a> | ||||
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| Ans. An Exception in java is the occurrence during computation that is anomalous and is not expected. Exception handling is the mechanism which is used to handle such situations. | ||||
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| Ans. [Open Ended Answer] The objective of the question is to check how efficient one is in the language so that appropriate level questions are asked. Don't tell too high number if you are being interviewed for a junior or mid level position as the interviewer may throw advance level questions. | ||||
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| Ans. Core: [Core, Bean, Context, Expression Language] Web: [Web, Portlet, Servlet, etc] Data Access [JMS, JDBC, etc] AOP, Aspect | ||||
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| Ans. Amazon Elastic Compute Cloud or EC2 provides scalable computing capacity in the AWS cloud. It can be used to create Virtual Environments , storage and configure. EC2 enables to upgrade or downgrade infrastructure according to the rules defined ( with fluctuation in latency, traffic etc ) | ||||
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| Ans. string and wrapper class objects | ||||
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| 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. | ||||
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| 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. | ||||
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| Ans. To fetch records from a database, you would use SELECT statements | ||||
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| Ans. The most effective and acceptable reasons for leaving your current job should be positive e.g. moving forward in your life or career | ||||
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| Ans. Assigning a value of one type to a variable of another type is known as Type Casting. Example : int x = 10; byte y = (byte)x; In Java, type casting is classified into two types, Widening Casting(Implicit) widening-type-conversion and Narrowing Casting (Explicitly done) narrowing-type-conversion. Widening or Automatic type converion - Automatic Type casting take place when,the two types are compatible and the target type is larger than the source type Example : public class Test { public static void main(String[] args) { int i = 100; long l = i; //no explicit type casting required float f = l;//no explicit type casting required System.out.println("Int value " i); System.out.println("Long value " l); System.out.println("Float value " f); } } Narrowing or Explicit type conversion - When you are assigning a larger type value to a variable of smaller type, then you need to perform explicit type casting. Example : public class Test{ public static void main(String[] args) { double d = 100.04; long l = (long)d; //explicit type casting required int i = (int)l;//explicit type casting required System.out.println("Double value " d); System.out.println("Long value " l); System.out.println("Int value " i); } } | ||||
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| Ans. Inline functions , just like C++ Macros is an optimized technique used by compiler to reduce the execution time. If the function is working on pre identified values ( which aren't resolved at runtime ), the function can execute the method and evaluate the outcome at compile time only instead of making a function call at runtime. | ||||
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| Ans. If there is a situation to remove duplicates values from an arrayList. Developer implemented using legacy for-loop where I suggested to use Linked hash set to remove duplicates from the list. | ||||
| Ans. Spring Boot aims to shorten the code length and provide you with the easiest way to develop a web application. It helps create a stand-alone application with less or almost zero-configuration. | ||||
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| Ans. Message queues implement an asynchronous communication pattern between two or more processes/threads whereby the sending and receiving party do not need to interact with the message queue at the same time. Messages placed onto the queue are stored until the recipient retrieves them. Message queues have implicit or explicit limits on the size of data that may be transmitted in a single message and the number of messages that may remain outstanding on the queue. | ||||