Star patterns in java

//File name--> Pattern.java

import java.io.*;
class Pattern{
 public static void main(String args[])throws Exception
 {
  BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
  
  System.out.println("Enter your choice to print different pattern(1-5):");
  int choice=Integer.parseInt(br.readLine());
  System.out.println("Enter Number of lines you want:");
  int n=Integer.parseInt(br.readLine());
  switch(choice)
  {
   case 1:
       for(int i=1;i < =n;i++)
       {
        System.out.println();

        for(int j=1;j < =i;j++)
         System.out.print(" ");
        
        int a=i; 
        for(int k=0;k < =n-i;k++)
        {
         System.out.print(" "+a);
         a+=i;
        }
       }
       break;
   case 2:
       for(int i=0;i < n;i++)
       {
        System.out.println();

        for(int j=0;j < i;j++)
         System.out.print(" ");
         
        for(int k=0;k < n-i;k++)
         System.out.print("* ");
       }
         
       break;
   case 3:
       for(int i=0;i < n/2+1;i++)
       {
        System.out.println();

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



   case 4:
       for(int i=0;i < n;i++)
       {
        System.out.println();

        for(int j=0;j < i;j++)
         System.out.print(" ");
         
        for(int k=0;k < n-i;k++)
          System.out.print("*");
       }  
       break;
   case 5:
       for(int i=0;i < n/2+1;i++)
       {
        System.out.println();

        for(int j=0;j < n/2-i;j++)
         System.out.print(" ");
         
        for(int k=0;k < =i;k++)
         System.out.print("*");
       }
       for(int i=0;i < n/2;i++)
       {
        System.out.println();
        for(int j=0;j < =i;j++)
         System.out.print(" ");
         
        for(int k=0;k < n/2-i;k++)
         System.out.print("*");
       }
       break;
   default:
       System.out.println("Invalid choice");
           
  }
  
 }
}

OUTPUT

javac Pattern.java

java Pattern
Enter your choice to print different pattern(1-5):
1
Enter Number of lines you want:
5

  1 2 3 4 5
   2 4 6 8
     3 6 9
      4 8
        5
java Pattern
Enter your choice to print different pattern(1-5):
2
Enter Number of lines you want:
5

* * * * *
 * * * *
   * * *
     * *
      *
java Pattern
Enter your choice to print different pattern(1-5):
3
Enter Number of lines you want:
7

    *
   * *
  * * *
* * * *
  * * *
   * *
     *

java Pattern
Enter your choice to print different pattern(1-5):
4
Enter Number of lines you want:
6

******
  *****
    ****
      ***
        **
          *
java Pattern
Enter your choice to print different pattern(1-5):
5
Enter Number of lines you want:
5

    *
  **
***
  **
    *