Drawing exercise in java

Question

I should do this program in java that asks me to write a program that issues a V composed of asterisks like the following picture:

        *
       *
*     *
 *   *
  * *
   *

This is the program that I created but it does not work:

import java.util.*;

public class Disegnav{
  public static void main (String [] arg){
    Scanner sc = new Scanner(System.in);
    for(int i = 5; i>0; i--){
        int k = 9, l=0, x=3;
        for(int j = 0; j<=9 ; j++){
            if(i>3 && j<k)
                System.out.print(" ");
            else
                if(j==k || i==l || i==x)
                    System.out.print("*");
                else
                    System.out.print(" ");
            k--;
            l++;
            x--;
        }
        System.out.println();
    }
  }
}

Answer 1

Ok I can give you an algorithm but you will have to try it out yourself.

Observe that for the first line no of spaces is 7 and then a * . Try printing that.

Same is for the second line but 6 spaces and a * .

Observe that from third line there are * on both the sides. So going by the same logic print a * then 5 spaces and a * .The observe since there are stars on both the sides, you need to decrease the space count by 2 .And at the same time increase the space count by 1 before printing the first * on each line. Hope you get it.

and do it iteratively until there is no space count left.

Answer 2

A general solution for problem.

import java.util.*;

public class Disegnav{
  public static void main (String [] arg){
    Scanner sc = new Scanner(System.in);
    int param = sc.nextInt() - 1;
    for(int i = 0; i < param; i++){
        for (int j = 0; j < i; j++) {
          System.out.print(" ");
        }
        System.out.print("*");
        for (int j = 0; j < 2 * param - 2 * i - 1; j++) {
          System.out.print(" ");
        }
        System.out.print("*");
        System.out.println();
    }
    for (int i = 0; i < param; i++) {
      System.out.print(" ");
    }
    System.out.print("*");
    System.out.println();
  }
}

Answer 3

Why so complicated? Let's keep it short!

class Draw {
    public static void main(String... args) {
        for (int x = -2, y = 8; x <= 3; ++x) {
            String before = (x >= 0) ? String.format("%" + (x+1) + "s", "*") : "";
            String after = (y > 0) ? String.format("%" + (y+1) + "s", "*") : "";
            System.out.println(before + after);
            y -= (x >= -1) ? 2 : 1;
        }
    }
}

I know this might be quite cryptic at first, but I can make some briefly explanation, in case you liked this one.

Also note, that this doesn't solve general problem, there are hard-coded size constants which are solving the problem only for your case.

I'm also assuming from the question, you didn't want to find bug in your program.

Answer 4

I don't know task conditions but the simplest way is :

public static void main (String [] arg){
System.out.println("        *\n" +
    "       *\n" +
    "*     *\n" +
    " *   *\n" +
    "  * *\n" +
    "   *");

}