Java打印金字塔（正实心、正空心，倒实心、倒空心），菱形

package com.cy.basic;

/**

• n表示打印几行

• i控制每一行

• j控制*的个数

• k控制空格数

• 解题就干一件事：找j,k与i的关系（规律）
  */
  public class PrintPyramid {

  public static void main(String[] args) {
  int n = 6;
  printPyramid(n); //打印实心金字塔
  System.out.println("------------------------------------------");
  printReversedPyramid(n); //打印倒的实心金字塔
  System.out.println("------------------------------------------");
  printHollowPyramid(n); //打印空心金字塔
  System.out.println("------------------------------------------");
  printReversedHollowPyramid(n); //打印倒的空心金字塔
  System.out.println("------------------------------------------");
  printRhombus(n); //打印实心菱形
  System.out.println("------------------------------------------");
  printHollowRhombus(n); //打印空心菱形
  }

  /*
  打印正的实心金字塔
  *
  ***
  *****
  *******
  /
  private static void printPyramid(int n) {
  for (int i = 1; i <= n ; i++) {
  for (int k = 1;k <= n - i;k++) {
  System.out.print(" ");
  }
  for (int j = 1;j <= 2 * i - 1;j++) {
  System.out.print("");
  }
  System.out.println();
  }
  }

  /*
  打印倒的实心金字塔
  *******
  *****
  ***
  *
  /
  private static void printReversedPyramid(int n) {
  for (int i = 1; i <= n ; i++) {
  for (int k = 1;k < i;k++) {
  System.out.print(" ");
  }
  /
  先死后活法找规律
  先死：
  n = 4; 2 * n - 1
  i 1 2 3 4
  *个数 7 5 3 1
  规律：7 + (i - 1) * (-2)
  后活：
  (2 * n - 1) + (i - 1) * (-2) = 2 * n - 2 * i + 1
  /
  for (int j = 1;j <= 2 * n - 2 * i + 1;j++) {
  System.out.print("");
  }
  System.out.println();
  }
  }

  /*
  打印正的空心金字塔
  *
  * *
  * *
  *******
  /
  private static void printHollowPyramid(int n) {
  for (int i = 1; i <= n ; i++) {
  if (i == 1) {
  for (int k = 1;k <= n - 1;k++) {
  System.out.print(" ");
  }
  System.out.println("");
  } else if (i == n) {
  for (int j = 1; j <= 2 * n - 1 ; j++) {
  System.out.print("");
  }
  System.out.println();
  } else {
  for (int k = 1;k <= n - i;k++) {
  System.out.print(" ");
  }
  System.out.print("");
  for (int k = 1; k <= 2 * i - 3 ; k++) {
  System.out.print(" ");
  }
  System.out.print("*");
  System.out.println();
  }
  }
  }

  /*
  打印倒的空心金字塔
  *******
  * *
  * *
  *
  /
  private static void printReversedHollowPyramid(int n) {
  for (int i = 1; i <= n; i++) {
  if (i == 1) {
  for (int j = 1; j <= 2 * n - 1 ; j++) {
  System.out.print("");
  }
  System.out.println();
  } else if (i == n) {
  for (int k = 1;k <= n - 1;k++) {
  System.out.print(" ");
  }
  System.out.println("");
  } else {
  for (int k = 1;k <= i - 1;k++) {
  System.out.print(" ");
  }
  System.out.print("");
  for (int k = 1; k <= 2 * n - 2 * i - 1 ; k++) {
  System.out.print(" ");
  }
  System.out.print("*");
  System.out.println();

       }
   }
  

  }

  /*
  打印实心菱形
  *
  ***
  *****
  *******
  *****
  ***
  *
  /
  private static void printRhombus(int n) {
  for (int i = 1; i <= n - 1 ; i++) {
  for (int k = 1;k <= n - i;k++) {
  System.out.print(" ");
  }
  for (int j = 1;j <= 2 * i - 1;j++) {
  System.out.print("");
  }
  System.out.println();
  }
  printReversedPyramid(n);
  }

  /*
  打印空心菱形
  *
  * *
  * *
  * *
  * *
  * *
  *
  /
  private static void printHollowRhombus(int n) {
  for (int i = 1; i <= n - 1 ; i++) {
  if (i == 1) {
  for (int k = 1;k <= n - 1;k++) {
  System.out.print(" ");
  }
  System.out.println("");
  } else if (i == n) {
  for (int j = 1; j <= 2 * n - 1 ; j++) {
  System.out.print("");
  }
  System.out.println();
  } else {
  for (int k = 1;k <= n - i;k++) {
  System.out.print(" ");
  }
  System.out.print("");
  for (int k = 1; k <= 2 * i - 3 ; k++) {
  System.out.print(" ");
  }
  System.out.print("*");
  System.out.println();
  }
  }

   for (int i = 1; i <= n; i++) {
       if (i == 1) {
           System.out.print("*");
           for (int k = 1; k <= 2 * n - 3 ; k++) {
               System.out.print(" ");
           }
           System.out.print("*");
           System.out.println();
       } else if (i == n) {
           for (int k = 1;k <= n - 1;k++) {
               System.out.print(" ");
           }
           System.out.println("*");
       } else {
           for (int k = 1;k <= i - 1;k++) {
               System.out.print(" ");
           }
           System.out.print("*");
           for (int k = 1; k <= 2 * n - 2 * i - 1 ; k++) {
               System.out.print(" ");
           }
           System.out.print("*");
           System.out.println();
  
       }
   }
  

  }

}