# Fibonacci series in java

Let’s learn Fibonacci series in java.

## Fibonacci series in java

A fibonacci series is a sequence where next number is sum of previous two numbers. Fibonacci sequence series : 0, 1, 1, 2, 3, 5, 8, 13, 21 . . . . .

Let’s see program for fibonacci series in java.

```public class FibonacciSeriesForLoop
{
public static void main(String[] args)
{
int f = 10, num1 = 0, num2 = 1;
System.out.print("First " + f + " fibonacci sequence: ");
for(int a = 1; a <= f; ++a)
{
System.out.print(num1 + " + ");
int total = num1 + num2;
num1 = num2;
num2 = total;
}
}
}
```

Output:

First 10 fibonacci sequence: 0 + 1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 +

In the above java program,

• Initially first two numbers in fibonacci series are fixed. That is, 0 and 1.
• Next number in the fibonacci series will be the sum of previous two numbers and so on. The fibonacci series continues.
• Now the logic here is first create two variables ‘a’ and ‘b’ having values 0 and 1. Also create variable int number.
• Then in the for loop iterate variable ‘i’ equal to one to ‘i’ less than or equal to 10 (for loop executing 10 times).
• Now ‘number’ is equal to ‘a’ plus ‘b’. Meanwhile print ‘number’ on the console using System.out.println
• Now assign value ‘b’ to ‘a’ and value ‘number’ to ‘b’. By doing this we are swapping values inside for loop.

Fibonacci program in java using while loop

```public class FibonacciSeriesWhileLoop
{
public static void main(String[] args)
{
int a = 1, num = 15, num1 = 0, num2 = 1;
System.out.print("First " + num + " fibonacci sequence: ");
while(a <= num)
{
System.out.print(num1 + " , ");
int total = num1 + num2;
num1 = num2;
num2 = total;
a++;
}
}
}
```

Output:

First 15 fibonacci sequence: 0 , 1 , 1 , 2 , 3 , 5 , 8 , 13 , 21 , 34 , 55 , 89 , 144 , 233 , 377 ,

Fibonacci series using recursion

```public class FibonacciRecursion
{
static int num1 = 0, num2 = 1, num3 = 0;
public static void main(String[] args)
{
System.out.print(num1 + " " + num2);
FibonacciRecursion obj = new FibonacciRecursion();
obj.fibonacciRecursive(14);
}
void fibonacciRecursive(int f)
{
if(f > 0)
{
num3 = num1 + num2;
System.out.print(" " + num3);
num1 = num2;
num2 = num3;
// fibonacci recursion
fibonacciRecursive(f - 1);
}
}
}
```

Output:

0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610