Java Program to find fibonacci series of a number

Program

import java.util.Scanner;
public class FibonacciSeries {
    public static void main(String args[]) {
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter the range of Fibonacci series");
        int range = sc.nextInt();
        if (range & lt; = 0) {
            System.out.println("Cannot generate Fibonacci series");
            System.exit(0);
        }
        int first = 0;
        int second = 1;
        System.out.println("Fibonacci Series:");
        if (range == 1)
            System.out.println(first);
        else if (range & gt; = 2) {
            System.out.print(first + "\t" + second);
            for (int i = 0; i & lt; range - 2; i++) {
                int fib = first + second;
                System.out.print("\t" + fib);
                first = second;
                second = fib;
            }
            System.out.println();
        }
    }
}

Let’s break down your FibonacciSeries program in the same simple format as your example:

• import java.util.Scanner;: This imports the Scanner class, which allows the program to take input from the user.
• public class FibonacciSeries: Every Java program starts with a class. Here, the class name is FibonacciSeries.
• public static void main(String args[]): The main method is the entry point for any Java program. Execution begins from here.
• Scanner sc = new Scanner(System.in);: Creates a Scanner object (sc) to read user input.

System.out.println("Enter the range of fibonacci series");
int range = sc.nextInt();

• Prompts the user to enter the range (number of Fibonacci terms).
• Reads the integer input using sc.nextInt() and stores it in the variable range.

if (range <= 0) {
    System.out.println("Cannot generate fibonacci series");
    System.exit(0);
}

• Checks if the input (range) is less than or equal to 0.
• If true, prints an error message and stops execution.

int first = 0;
int second = 1;
System.out.println("Fibonacci Series:");

• Initializes the first two terms of the Fibonacci series (first = 0, second = 1).
• Prints a header for the Fibonacci series.

if (range == 1)
    System.out.println(first);

• If the user specifies range = 1, the program prints only the first term (0).

else if (range >= 2) {
    System.out.print(first + "\t" + second);
}

• If the user specifies range >= 2, the program prints the first two terms (0 and 1).

for (int i = 0; i < range - 2; i++) {
    int fib = first + second;
    System.out.print("\t" + fib);
    first = second;
    second = fib;
}

• Calculates and prints the remaining Fibonacci terms:
  • Adds the last two terms (first + second) to get the next term (fib).
  • Updates first and second to proceed to the next iteration.
  • This continues until the required range is covered.

Execution:

1. Initializes: first = 0, second = 1.
2. Prints: 0, 1.
3. Loop:
   • Iteration 1: fib = 0 + 1 = 1, prints 1.
   • Iteration 2: fib = 1 + 1 = 2, prints 2.
   • Iteration 3: fib = 1 + 2 = 3, prints 3.
   • Iteration 4: fib = 2 + 3 = 5, prints 5.
   • Iteration 5: fib = 3 + 5 = 8, prints 8.
   • Iteration 6: fib = 5 + 8 = 13, prints 13.

Output

Enter the range of Fibonacci series
8
Fibonacci Series:
0	1	1	2	3	5	8	13