# Fibonacci Series Program in Java

Fibonacci series in Java | In the Fibonacci series, the next element will be the sum of the previous two elements. The Fibonacci sequence is a series of numbers where a number is found by adding up the two numbers before it. Starting with 0 and 1, the sequence goes 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, and so on…

By definition, the first two numbers in the Fibonacci sequence are either 1 and 1, or 0 and 1, depending on the chosen starting point of the sequence, and each subsequent number is the sum of the previous two.

As a rule, the expression is Xn= Xn-1+ Xn-2

``````import java.util.Scanner;

public class FibonacciSeries {

public static void displayFibonacci(int term) {

// declare variables
int t1 = 0; // first term
int t2 = 1; // second term
int n; // nth term
int i = 1; // iterator variable

while(i <= term) {

// display ith terms
System.out.print(t1+"\t");

// update term values
n = t1 + t2;
t1 = t2;
t2 = n;

// increase iterator variable
// value by 1
i++;
}
}

public static void main(String[] args) {

int terms; // number of terms

// Read number of terms to display
Scanner scan = new Scanner(System.in);
System.out.print("Enter number of terms: ");
terms = scan.nextInt();

// display Fibonacci series
System.out.println("The Fibonacci series: ");
displayFibonacci(terms);

// close Scanner class object
scan.close();
}
}``````

The output for different test-cases:-

Enter number of terms: 7
The Fibonacci series:
`0 1 1 2 3 5 8`

Enter number of terms: 10
The Fibonacci series:
`0 1 1 2 3 5 8 13 21 34`

The above Fibonacci series program in Java is developed by using a while loop. We can also use for loop to find the Fibonacci series.

## Using for loop

``````public static void displayFibonacci(int term) {

int t1 = 0; // first term
int t2 = 1; // second term
int n; // nth term

for(int i=1; i <= term; i++) {

// display ith terms
System.out.print(t1+"\t");

// update term values
n = t1 + t2;
t1 = t2;
t2 = n;
}
}``````

## Fibonacci series program in Java up to a given number

We can also display the Fibonacci series up to a given number. In this case, again we can use any looping statement like for loop or while loop or do-while loop.

``````import java.util.Scanner;

public class FibonacciSeries {

public static void displayFibonacci(int range) {

// declare variables
int t1 = 0; // first term
int t2 = 1; // second term
int n; // nth term

while(t1 <= range) {

//display the term
System.out.print(t1+"\t");

// update term values
n = t1 + t2;
t1 = t2;
t2 = n;
}
}

public static void main(String[] args) {
int range; // range value

Scanner scan = new Scanner(System.in);
System.out.print("Enter range: ");
range = scan.nextInt();

// display Fibonacci series
System.out.println("The Fibonacci series"
+ " upto "+range+" is: ");
displayFibonacci(range);

// close Scanner class object
scan.close();
}
}``````

The output for the different test-cases:-

Enter range: 20
The Fibonacci series up to 20 is:
`0 1 1 2 3 5 8 13`

Enter range: 100
The Fibonacci series up to 100 is:
`0 1 1 2 3 5 8 13 21 34 55 89`

Enter range: 1000
The Fibonacci series up to 1000 is:
`0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987`

## Finding Nth Fibonacci term in Java

``````import java.util.Scanner;

public class FibonacciSeries {

public static int nthFibonacciTerm(int term) {

int t1 = 0; // first term
int t2 = 1; // second term
int n = 0; // nth term

if(term==1) return t1;
if(term==2) return t2;

// 2 terms are already exist so
// iterator variable should
for(int i=3; i <= term; i++) {

// update term values
n = t1 + t2;
t1 = t2;
t2 = n;
}

return n;
}

public static void main(String[] args) {

int n; // range value

Scanner scan = new Scanner(System.in);
System.out.print("Enter n value: ");
n = scan.nextInt();

// display Fibonacci series
System.out.println(n+" Fibonacci term "
+ " is = "+ nthFibonacciTerm(n));

// close Scanner class object
scan.close();
}
}``````

The output for the different test-cases:-

Enter n value: 1
1 Fibonacci term is = 0

Enter n value: 2
2 Fibonacci term is = 1

Enter n value: 7
7 Fibonacci term is = 8

Enter n value: 10
10 Fibonacci term is = 34

We can also find the Fibonacci series using the recursion technique. For more see:- Fibonacci series using recursion

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