Java Interview Programs:
2)Fibonacci Series using recursion in java

class FibonacciExample2
{ 
static int n1=0,n2=1,n3=0;   
static void printFibonacci(int count)
{   
    if(count>0)
     {   
         n3 = n1 + n2;   
         n1 = n2;   
         n2 = n3;   
         System.out.print(" "+n3);  
         printFibonacci(count-1);   
     }   
}   
public static void main(String args[])
{   
  int count=10;   
  System.out.print(n1+" "+n2);
  //printing 0 and 1   
  printFibonacci(count-2);
//n-2 because 2 numbers are already printed  
} 
}

Java Interview Programs:
!) Fibonacci Series in Java without using recursion

class FibonacciExample1
{ 
public static void main(String args[]) 
{   
int n1=0,n2=1,n3,i,count=10;   
System.out.print(n1+" "+n2);

//printing 0 and 1   
   
for(i=2;i<count;++i)
//loop starts from 2 because 0 and 1 are already printed   
{   
  n3=n1+n2;   
  System.out.print(" "+n3);   
  n1=n2;   
  n2=n3;   
}   
 
}
}

All this program is very important for freshers

What do you understand by copy constructor in Java?
There is no copy constructor in java. However, we can copy the values from one object to another like copy constructor in C++.
There are many ways to copy the values of one object into another in java. They are:
By constructor
By assigning the values of one object into another
By clone() method of Object class
In this example, we are going to copy the values of one object into another using java constructor.
https://cjavapoint.blogspot.com/2023/09/Java%20Inheritance%20Update.html

What is JDBC?
JDBC is a Java API that is used to connect and execute the query to the database. JDBC API uses JDBC drivers to connect to the database. JDBC API can be used to access tabular data stored into any relational database.

What are the JDBC statements?
In JDBC, Statements are used to send SQL commands to the database and receive data from the database. There are various methods provided by JDBC statements such as execute(), executeUpdate(), executeQuery, etc. which helps you to interact with the database.

What is the return type of Class.forName() method?
The Class.forName() method returns the object of java.lang.Class object

For more information visit
https://cjavapoint.blogspot.com/2023/09/Java%20Inheritance%20Update.html

How can we set null value in JDBC PreparedStatement?
By using setNull() method of PreparedStatement interface, we can set the null value to an index. The syntax of the method is given below.

void setNull(int parameterIndex, int sqlType) throws SQLException  
      

What is the role of the JDBC DriverManager class?
The DriverManager class acts as an interface between user and drivers. It keeps track of the drivers that are available and handles establishing a connection between a database and the appropriate driver. The DriverManager class maintains a list of Driver classes that have registered themselves by calling the method DriverManager.registerDriver().

What are the functions of the JDBC Connection interface?
The Connection interface maintains a session with the database. It can be used for transaction management. It provides factory methods that return the instance of Statement, PreparedStatement, CallableStatement, and DatabaseMetaData.

What is the difference between HashSet and TreeSet?
The HashSet and TreeSet, both classes, implement Set interface. The differences between the both are listed below.
HashSet maintains no order whereas TreeSet maintains ascending order.
HashSet impended by hash table whereas TreeSet implemented by a Tree structure.
HashSet performs faster than TreeSet.
HashSet is backed by HashMap whereas TreeSet is backed by TreeMap.

What is the difference between Set and Map?
The differences between the Set and Map are given below.
Set contains values only whereas Map contains key and values both.
Set contains unique values whereas Map can contain unique Keys with duplicate values.
Set holds a single number of null value whereas Map can include a single null key with n number of null values.

What is the difference between HashSet and HashMap?
The differences between the HashSet and HashMap are listed below.
HashSet contains only values whereas HashMap includes the entry (key, value). HashSet can be iterated, but HashMap needs to convert into Set to be iterated.
HashSet implements Set interface whereas HashMap implements the Map interface
HashSet cannot have any duplicate value whereas HashMap can contain duplicate values with unique keys.
HashSet contains the only single number of null value whereas HashMap can hold a single null key with n number of null values.

What is the difference between HashMap and TreeMap?
The differences between the HashMap and TreeMap are given below.
HashMap maintains no order, but TreeMap maintains ascending order.
HashMap is implemented by hash table whereas TreeMap is implemented by a Tree structure.
HashMap can be sorted by Key or value whereas TreeMap can be sorted by Key.
HashMap may contain a null key with multiple null values whereas TreeMap cannot hold a null key but can have multiple null values.

What is the difference between Collection and Collections?
The differences between the Collection and Collections are given below.
The Collection is an interface whereas Collections is a class.
The Collection interface provides the standard functionality of data structure to List, Set, and Queue. However, Collections class is to sort and synchronize the collection elements.
The Collection interface provides the methods that can be used for data structure whereas Collections class provides the static methods which can be used for various operation on a collection.

For more information visit
https://cjavapoint.blogspot.com/2023/09/Java%20Inheritance%20Update.html

HAS-A Relationship
1.HAS-A Relationship is also knows as composition(or) aggregation.
2.There is no specific keyword to implement HAS-A relationship but mostly
we can use new operator.
3.The main advantage of reusability.

Example:-
class Engine
{
// engine functionality
}
class Car
{
Engine e=new Engine();
//------------------------------;
//------------------------------;
//------------------------------;
}
NOTE:-
class car has-a engine reference.
The main dis-advantage of has-a relationship increases dependency between the
components and creates maintains problems. 👌👌👌👌👌👌 More java interview Questions Visit: -https://cjavapoint.blogspot.com/👈👈👈👈👈

Core Java Inetrview Questions java Opps Concept What is method overloading in OOP or Java? (answer)
It's one of the oldest OOPS concept questions, I have seen it 10 years ago and still sees it now. When we have multiple methods with the same name but different functionality then it's called method overloading. For example. System.out.println() is overloaded as we have 6 or 7 println() method each accepting a different type of parameter.


What is method overriding in OOP or Java? (answer)
It's one of the magic of object oriented programming where the method is chose based upon an object at runtime. In order for method overriding, we need Inheritance and Polymorphism, as we need a method with the same signature in both superclass and subclass. A call to such method is resolved at runtime depending upon the actual object and not the type o variable. See the answer for more detailed discussion. more Questions Visit https://cjavapoint.blogspot.com/👌👌👌👈👈👈👈

What is method overloading?

Method overloading is a programming technique that allows developers to use the same method name multiple times in the same class, but with different parameters. In this case, we say that the method is overloaded. Listing 1 shows a single method whose parameters differ in number, type, and order.
Listing 1. Three types of method overloading


Number of parameters:
public class Calculator {
void calculate(int number1, int number2) { }
void calculate(int number1, int number2, int number3) { }
}

Type of parameters:
public class Calculator {
void calculate(int number1, int number2) { }
void calculate(double number1, double number2) { }
}

Order of parameters:
public class Calculator {
void calculate(double number1, int number2) { }
void calculate(int number1, double number2) { }
} more java interview Questions visit https://cjavapoint.blogspot.com/ join my me on https://t.me/javaQuestions4u 👌👌👌👌👍👍👍👍

Strings in Java
Strings in Java are Objects that are backed internally by a char array. Since arrays are immutable(cannot grow), Strings are immutable as well. Whenever a change to a String is made, an entirely new String is created.

Below is the basic syntax for declaring a string in Java programming language.
Syntax: String str = "learnJava";
More java Interview Questions Visit:- https://cjavapoint.blogspot.com/ 👌👌👌👌👌👌