Java – ピラミッドの印刷方法

package com.mkyong;

import java.util.Collections;

public class CreatePyramid {

    public static void main(String[]args) {

        int rows = 5;

        System.out.println("\n1. Half Pyramid\n");
        for (int i = 0; i < rows; i++) {

            for (int j = 0; j <= i; j++) {
                System.out.print("** ");
            }

            System.out.println("");
        }

        System.out.println("\n2. Full Pyramid\n");
        for (int i = 0; i < rows; i++) {

            for (int j = 0; j < rows - i; j++) {
                System.out.print(" ");
            }

            for (int k = 0; k <= i; k++) {
                System.out.print("**  ");
            }

            System.out.println("");
        }

       //java 8 , one line
        System.out.println("\n3. Full Pyramid (Compact)\n");
        for (int i = 0; i < rows; i++) {

            System.out.println(String.join("", Collections.nCopies(5 - i - 1, " "))
                    + String.join("", Collections.nCopies(2 **  i + 1, "** ")));

        }

       //java 8
        System.out.println("\n4. Inverted Pyramid\n");
        for (int i = rows; i > 0; i--) {

            System.out.println(String.join("", Collections.nCopies(5 - i, " "))
                    + String.join("", Collections.nCopies(2 **  i - 1, "** ")));

        }

    }

}

1. Half Pyramid

**
** **

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

** ** ** ** **

2. Full Pyramid

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

3. Full Pyramid (Compact)

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

4.反転ピラミッド

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