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Q871. How can i split a linked list in two parts in java 8?

Ans. This can be done using a Spliterator.

LinkedList list = Arrays.asList("names","numbs","birds","animals");
Spliterator split1 = list.Spliterator();
Spliterator split2 = split1.Spliterator();

Now, the LinkedList is split into split1 and split2.
use split2 first then split1 to check the output.

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Q872. What is difference between Spring jdbc template and Hibernate ?

Hibernate

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Q873. Explain OOps concepts.

Core Java

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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Q874. How to configure Tomcat to have number of user restrictions?

Server

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Q875. What is collection framework in Java ?

Core Java

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.

Sample Code for Map

Sample Code for HashMap

Sample Code for Treemap

Sample Code for set

Sample Code for hashset

Sample Code for treeset

Sample Code for list

Sample Code for arraylist

Sample Code for linkedlist

Sample Code for queue

Sample Code for priorityqueue

Sample Code for concurrenthashmap

Sample Code for vector

Sample Code for stack

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Q876. What is difference between clustered and non clustered index?

Database

Ans. The clustered index determines how the data is stored in the rows of a table.The non-clustered index stores the data at a single place and the indexes are stored at another place.

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Q877. What are the ways to get the values from list ?

Data Structure

Ans. list.get(index);

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Q878. What is Left Outer Join ?

Database

Ans. It returns all the rows form the left table and matches the rows in both tables.

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Q879. How one dao Implementation object (singleton) can handle multiple requests?

Design Pattern

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Q880. What is an applet ?

Java EE

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Q881. How cloud computing is different than virtualization ?

Server

Ans. A Virtualization is software that virtualizes your hardware into multiple machines while Cloud computing is the combination of multiple hardware devices. In Virtualization, a user gets dedicated hardware while in Cloud computing multiple hardware devices provide one login environment for the user.

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Q882. Explain Facade design pattern

Design

Ans. Single gateway of the entire application is called Facade Design Pattern.

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Q883. Find Max from Stack in O(1) complexity

Algorithm

Ans. Create one extra field called MAX O(1)

when you an element to the stack check these two condition
1. Stack is empty, then MAX = element
2. Stack is not empty then check if the element is greater than MAX then MAX = element

when getMax fuction is called, then return MAX

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Q884. In the Following code which foo will get called.

foo(Integer i){
}

foo(String s){
}

public static void main(){
passing foo(null);
}

Core Java

Ans. ambiguity error

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Q885. Can you give a real life example of synchronization

Core Java

Ans. Intersection with traffic light

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Q886. What is the difference between AWS Gateway API and Lambda ?

Amazon Web Services (AWS)

Ans. AWS API Gateway is the endpoint URI to get invoke. Whereas Lambda is the compute function being invoked from API Gateway or S3 or SNS

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Q887. Can we build web services using AWS Lambda ?

Amazon Web Services (AWS)

Ans. We have to complement it to AWS Gateway API.

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Q888. Can we modify a list while iterating it ?

Core Java

Ans. No,we cannot.I t will give concurrentModificationExceptin error. It can be resolved by using ConcurrentClasses like ConcurrentHashMap,CopyOnWriteArrayList,BlockingQueue etc which are fail-safe and wont give exception.

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Q889. How is RDBMS different from DBMS ?

Database

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Q890. What is the use of second level cache in Hibernate ?

Hibernate

Ans. Second level cache is shared between sessions. Hibernate by default uses first level cache. Second level cache need to be configurd to use.
There are several second level cache e.g eh cache,jboss cache etc.

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Q891. Describe SQL Joins

Database

Ans. Oracle having following types of joins these are also called 8i joins. There are:

1. Equi (or) Inner join
2. Non Equi join
3.Self join
4.Outer join

Oracle also support the 9i (or) ANSI standard joins.There are:

1.Inner join
2.Left outer join
3.Right outer join
4.Full outer join
5.Natural join

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Q892. Write code for serialization.

Core Java

Ans. // Java code for serialization and deserialization
// of a Java object
import java.io.*;

class Demo implements java.io.Serializable
{
   public int a;
   public String b;

   // Default constructor
   public Demo(int a, String b)
   {
      this.a = a;
      this.b = b;
   }

}

class Test
{
   public static void main(String[] args)
   {
      Demo object = new Demo(1, "geeksforgeeks");
      String filename = "file.ser";

      // Serialization
      try
      {
         //Saving of object in a file
         FileOutputStream file = new FileOutputStream(filename);
         ObjectOutputStream out = new ObjectOutputStream(file);

         // Method for serialization of object
         out.writeObject(object);

         out.close();
         file.close();

         System.out.println("Object has been serialized");

      }

      catch(IOException ex)
      {
         System.out.println("IOException is caught");
      }

      Demo object1 = null;

      // Deserialization
      try
      {
         // Reading the object from a file
         FileInputStream file = new FileInputStream(filename);
         ObjectInputStream in = new ObjectInputStream(file);

         // Method for deserialization of object
         object1 = (Demo)in.readObject();

         in.close();
         file.close();

         System.out.println("Object has been deserialized ");
         System.out.println("a = " object1.a);
         System.out.println("b = " object1.b);
      }

      catch(IOException ex)
      {
         System.out.println("IOException is caught");
      }

      catch(ClassNotFoundException ex)
      {
         System.out.println("ClassNotFoundException is caught");
      }

   }
}

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Q893. How would you implement low latency data structures ?

Data Structure

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Q894. How do you fetch the records form database ?

Database

Ans. To fetch records from a database, you would use SELECT statements

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Q895. How to Create Cron Job in Hybris e-commerce suite

Hybris

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Q896. Which of the OOP's feature - encapsulation or abstraction - is more important ?

Core Java

Ans. Encapsulation facilitates security by hiding data and logic whereas Abstraction simplifies organization of data and related logic.

As applications scale, both concepts are required for easy management and maintenance. Encapsulation for security and criss cross communication between objects / modules will make it vulnerable. and Abstraction for better organization that enables better understanding of application code and easy maintainability.

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Q897. Which of the polymorphism type - static or runtime - is more important ?

Core Java

Ans. Method overloading / static polymorphism compared to method overriding / runtime polymorphism has very limited usage as it just opens up an alternate way of defining a different method with the same name.

Method Overriding on other hand opens up many other features like contracting , interfacing , pluging development and hence development of libraries and frameworks.

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Q898. What are scrollable ResultSet?

Database

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Q899. How to instantiate jsp variable from another jsp?

JSP

Ans. using session attribute.

session.setAttribute("userId",userId);

in first jsp

int userId=session.getAttribute("userId");

in second jsp;

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Q900. What will the following code print and Why

class Class1 {
static{
System.out.println("Wow");
}
public static final int xyz=1;
}

class Class2{
public static void main(String[] args) {
System.out.println(String.valueOf(Class1.xyz));
}
}

Core Java

Ans. 1

Reason being that Class1.xyz is replaced with 1 during pre compilation only and a reference to Class1 is never made.

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