NIIT Technologies Java Interview Questions
- 1) What is the difference between an interface and an abstract class?
- 2) Explain What is Spring MVC?
- 3) What is abstraction?
- 4) What is the difference between left and right outer join?
- 5) Explain how HashMap works?
- 6) Write a factorial program using recursion in Java?
- 7) What is Operator overloading. Is it is supported in java?
- 8) How to avoid memory leak in JAVA?
- 9) What is EnumSet?
- 10) How can we create a synchronized collection from given collection?
- 11) What is ceil and floor in Oracle?
- 12) What is Singleton design pattern?
- 13) What is Difference between equals and hashcode method?
- 14) Explain Dependency Injection and its types?
- 15) What is difference between String buffer and String builder ?
- 16) What is apply operator in sql?
- 17) What are 4 pillers of object orinted programming?
- 18) What are abstract functions? Why are they used?
Below are the list of Best NIIT Technologies Java Interview Questions and Answers
Spring MVC is a framework of Java used for developing web applications. It follows the design pattern of Model-View-Controller. A spring MVC gives an optimum solution to use the spring framework along with MVC. To do so, it takes the help of the DispatcherServlet that receives the incoming request and then implements it to a suitable resource including controllers, views, and models. Spring MVC has a number of advantages such as rapid development and ease of testing.
Abstraction is basically used to separate the useless data from the essential ones. Only the important things that need to be shown to the users are only being exposed. Here in these issues, the users get to view only the essential data which is actually required. It also helps in differentiating the object from any other similar object just by looking into the classification of features. It is a really efficient process of filtering.
EnumSet is basically used for coding purposes. Where there are a set of words that have the same meaning and can be denoted by a single word. Like for example, there are a set of words that consists of words like red, green, yellow, blue. These all words can be denoted by a single word which can be easily denoted by a single word like Colours. It is basically of high performance and is really reliable.
They both are basically opposite to each other. Here the Ceil it stands for the word Ceiling. It basically has a function to return the smallest value of an integer which is actually greater than or equal to the given number. The number here is basically rounded up to the nearest whole number.
On the other hand in the Floor function, it generally rounds down to the nearest whole number. This returns the highest integer value which may be equal to or less than the given number.
Singleton design pattern is a creational pattern that is used whenever only one instance an object is needed to be created. In this pattern, you can't initialize the class.
Dependency injection is way to pass one obeject dependencies to another object.It is a broader form of inversion of control (IOC).
There are basically 3 types of dependency injection:
- constructor injection
- setter injection
- Interface injection
In the year 2005, SQL server has introduced apply operator. This is basically a joining that shows the expression of the left table with the right table expression. The expressions that are basically produced in the right table expression is after following up each row in the left table. The left table expressions are calculated in the first hand and then the right table. After following this process we can get our final set value.
The four pillars of the OOPs are:
- Abstraction: Abstraction is basically used to separate unwanted things from the essential ones. Only important properties.
- Encapsulation: The encapsulation process consists of certain methods and properties of the abstraction process. It also protects these methods from any interference or tampering.
- Inheritance: Inheritance is of two types basically: single inheritance & multiple inheritances. It is how a class is derived from the other class.
- Polymorphism: Here in polymorphism, you can name it all the same for the different actions of an object of different data types.
The abstract function or method does not have a body and also it cannot be implemented. The abstract classes cannot be started without the help of the subclasses that help in providing the implementations which are actually for the abstract methods. They actually try developing base classes which help in the custom implementation. The keyword abstract can be used to denote both the abstract methods and also an abstract class.
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