Java Program to Print Fibonacci Series with Example Output

Ever wondered how to generate the Fibonacci series using Java? It's a cool sequence starting with 0 and 1. Each next number is just the sum of the last two. Let's dive into how to create this in Java!

For instance, if you want the first 5 terms, you’ll get: 0, 1, 1, 2, 3. In this article, you'll learn how to write a program for it.

Prerequisites for the Fibonacci Program in Java

Here’s what you’ll need to know to write the program:

• Basic understanding of for loops.
• Using int variables in Java.
• Java I/O — Scanner class for input.
• Any Java compiler like JDK 8 or run it in the EduSeekho online compiler.

Source Code of Java Program to Print Fibonacci Series

Here’s the complete source code to print the Fibonacci series up to n terms:

import java.util.Scanner;

public class FibonacciSeries {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter the number of terms: ");
        int n = input.nextInt();

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

        for (int i = 1; i <= n; i++) {
            System.out.print(first + " ");

            int next = first + second;
            first = second;
            second = next;
        }
    }
}

Output of the Fibonacci Series Program

When you enter the number of terms, this is the output:

Enter the number of terms: 5
Fibonacci Series: 0 1 1 2 3

Algorithm to Print Fibonacci Series in Java

Generating the Fibonacci series involves adding the last two numbers to get the next one. Here's how this program achieves it:

1. Read the number of terms n from the user.
2. Initialize first to 0 and second to 1.
3. Start a loop from 1 to n.
4. Print the first number.
5. Calculate next as the sum of first and second.
6. Update first to second and second to next.
7. Repeat steps 4-6 until all terms are printed.

flowchart TD
  A([Start]) --> B[/Read n/]
  B --> C["first = 0, second = 1"]
  C --> D["i = 1"]
  D --> E{"i <= n?"}
  E -->|Yes| F["print first"]
  F --> G["next = first + second"]
  G --> H["first = second, second = next"]
  H --> I["i = i + 1"]
  I --> E
  E -->|No| J([End])

How the Java Program to Print Fibonacci Works

Let's see what each part of the code does:

• import java.util.Scanner;: Imports the Scanner class for user input.
• public class FibonacciSeries: Declares the main class, matching the filename.
• main method: The entry point for the program, where the execution starts.
• Scanner input: Creates a Scanner object to read input from the user.
• System.out.print("Enter the number of terms: ");: Prompts the user to enter the number of terms.
• int n = input.nextInt();: Reads the number of terms as an integer.
• int first = 0, second = 1;: Initializes the first two numbers of the series.
• for loop: Iterates from 1 to n, printing and calculating Fibonacci numbers.
• System.out.print(first + " ");: Prints the current Fibonacci number.
• int next = first + second;: Computes the next Fibonacci number.
• first = second; and second = next;: Updates first and second for the next iteration.

Time and Space Complexity of the Java Program to Print Fibonacci Series

Understanding the complexity can help you gauge the efficiency of your solution.

Time Complexity: O(n). The loop runs n times to print n terms — 5 terms means 5 iterations. The code includes for (int i = 1; i <= n; i++).

Space Complexity: O(1). It uses only a fixed number of variables: first, second, next, and n — four integers regardless of input size.

Key takeaway:The Fibonacci sequence can be generated efficiently using iteration, showing how powerful simple loops can be.

FAQs About Java Program to Print Fibonacci Series

Here are some common questions about this program.

Related Programs

If you found this program helpful, check out these related programs:

• Java Program to Find Duplicate Characters in a String
• Java Program to Find Prime Number | Full Code and Output

Conclusion

Switching up the initial numbers lets you create similar series like Lucas numbers. Give it a go! It really broadens your grasp of numerical sequences. Once you're good with this code, try generating Fibonacci numbers recursively.

Test your skills with our Java quiz or play around with this code in the Java compiler online.