Fibonacci series in Java

Java Fibonacci series is a number series, the sum of the previous two numbers result is the next number.

e.g: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55 etc.

we can start our series from 0 or 1, it is our choice.

 There are two ways to write the Fibonacci series in Java:

=> Fibonacci series using for & while loop / without method recursion

=> Fibonacci series using method recursion

Let’s check the first Fibonacci series using for loop

public class FibonacciTest {     

       public static void main(String[] args) {       

              int number=10;

              int f1=0,f2=1,f3=0;       

              //System.out.print(f1); // print zero          

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

                    

                     f3=f1+f2;

                     f1=f2;

                     f2=f3;

                     f3=f1;

                     System.out.print(" "+f3);

              }            

       }

}

Output:

1 1 2 3 5 8 13 21 34 55

Understanding the flow of the program

int number=10;

int f1=0,f2=1,f3=0;       

for(int i=1; i<=number; i++)

Repeat loop until condition false 

f3=f1+f2;	f1=f2;	f2=f3;	f3=f1;	System.out.println( f3);
f3=0+1	f1=1	f2=1	f3=1	1
f3=1+1	f1=1	f2=2	f3=1	1
f3=1+2	f1=2	f2=3	f3=2	2
f3=2+3	f1=3	f2=5	f3=3	3
f3=3+5	f1=5	f2=8	f3=5	5
f3=5+8	f1=8	f2=13	f3=8	8
f3 store next print value			f3 store current print value	Continue like this……

I hope you guys understood the flow of this program J

Fibonacci series using method recursion

Method recursion is a method that calls itself continuously.

public class FibonacciTest {     

        static int f1=0,f2=1,f3=0;   

        static void printSeries(int count){   

           if(count<=10){   

                f3=f1+f2;   

                f1=f2;   

                f2=f3;

                f3=f1;

                System.out.print(" "+f3);

                count++;

                printSeries(count);   

            }   

        }   

        public static void main(String args[]){   

        

        // System.out.print(f1);//print 0   

               printSeries(1);

        } 

}

The Fibonacci program using method recursion is given the same output as above

Output:

1 1 2 3 5 8 13 21 34 55

Here we took static variables and methods because we can call it directly in the main method without creating the object.

The flow of this program is the same as the above program but here we used method recursion and repeat the if condition until false.