Introduction to Microservice Architecture Using SpringBoot - Part 1

How to print a butterfly pattern for a given value 

 Here we are assuming n=10 .

First part :

for the first half of the pattern we are printing "*" which is equal to row number . then we print "  " which is equal to 2*(n-row number). and after that we again print "*" which is equal to row number .

for first row i=1 and n=10 (given)

so at first we print one star and then print 2*(n-i) = 2*(10-1) =18 space. and then again print 1 star.

for the second row i=2 and n=10

so at first we print two(i) stars and then print 2*(n-i) = 2*(10-2) =16 space. and then again print two stars.

after completing each row we start from a new line .

we are following this pattern upto row number 10 . 

      for(int i=1;i<=n;i++)  
           {  
                for(int j=1 ;j<=i;j++)  
                {  
                     System.out.print("*");  
                }  
                for(int j=1 ;j<=2*(n-i);j++)  
                {  
                     System.out.print(" ");  
                }  
                for(int j=1 ;j<=i;j++)  
                {  
                     System.out.print("*");  
                }  
                System.out.println();  
           }  

---

Second part :

for second part we have to reverse the logic .

so for the first row of the second part we assuming i=n=10

so we are printing i=n=10 number of stars and then 2*(n-i)= 2*0=0 number of space and then again i=n=10 number of star 

so for the second row of the second part we assuming i=n=9

so we are printing i=n=9 number of stars and then 2*(n-i)= 2*1=2 number of space and then again i=n=9 number of star .

and we are repeating this for n times 

 for(int i=n;i>0;i--)  
           {  
                for(int j=1 ;j<=i;j++)  
                {  
                     System.out.print("*");  
                }  
                for(int j=1 ;j<=2*(n-i);j++)  
                {  
                     System.out.print(" ");  
                }  
                for(int j=1 ;j<=i;j++)  
                {  
                     System.out.print("*");  
                }  
                System.out.println();  
           }  

---

Full Code : 

 import java.lang.*;  
 import java.util.*;  
 public class butterflyPattern  
 {  
      public static void main(String[] args)  
      {  
           System.out.println("Enter the number : ");  
           Scanner sc= new Scanner(System.in);  
           int n = sc.nextInt();  
           for(int i=1;i<=n;i++)  
           {  
                for(int j=1 ;j<=i;j++)  
                {  
                     System.out.print("*");  
                }  
                for(int j=1 ;j<=2*(n-i);j++)  
                {  
                     System.out.print(" ");  
                }  
                for(int j=1 ;j<=i;j++)  
                {  
                     System.out.print("*");  
                }  
                System.out.println();  
           }  
           for(int i=n;i>0;i--)  
           {  
                for(int j=1 ;j<=i;j++)  
                {  
                     System.out.print("*");  
                }  
                for(int j=1 ;j<=2*(n-i);j++)  
                {  
                     System.out.print(" ");  
                }  
                for(int j=1 ;j<=i;j++)  
                {  
                     System.out.print("*");  
                }  
                System.out.println();  
           }  
      }  
 }