How should I remove this 2 lines between this pattern-CodePudding

static void k(){
    Scanner sc= new Scanner(System.in);
    System.out.println("no.of rows");
    int a = sc.nextInt();

    for(int row=a; row>=1; row--){

        for (int col=1; col <=row-1; col  ){
            System.out.print(" * ");
       }
       System.out.println();
    }
    for(int row=1; row<=a; row  ){

        for (int col=1; col <=row-1; col  ){
            System.out.print(" * ");
        }
        System.out.println();
    }
}

 *  *  *  *
 *  *  *
 *  *
 *


 *
 *  *
 *  *  *
 *  *  *  *

I am trying to print the above patterns in Java, but two extra lines are getting added between the patterns. I don't know how to remove them.

CodePudding user response：

Try this, ie inner loops without -1

for(int row=a; row>=1; row--){

    for (int col=1; col <=row; col  ){
        System.out.print(" * ");
   }
   System.out.println();
}
for(int row=1; row<=a; row  ){

    for (int col=1; col <=row; col  ){
        System.out.print(" * ");
    }
       System.out.println();
}

CodePudding user response：

You will have to add some conditions to your System.out.println() calls.

Also:

Use appropriate variable/method names, avoid using single-letter names
You should index at 0; it makes more logical sense

public class Main {
    public static void main(String[] args) {
        printTriangles();
    }
    private static void printTriangles() {
        //Scanner sc = new Scanner(System.in);
        //System.out.print("Number of rows: ");
        int rows = 4; // sc.nextInt();
        for (int row = rows; row > 0; row--) {
            for (int col = 0; col < row; col  ) {
                System.out.print(" * ");
           }
           if (row > 1) {
               System.out.println();
           }
        }
        for (int row = 0; row <= rows; row  ) {
            for (int col = 0; col < row; col  ) {
                System.out.print(" * ");
            }
            if (row < rows) {
               System.out.println();
           }
        }
    }
}

Output

Where input = 4

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