二重循环之打印图形例解

 1 package cn.happy.shape;
 2 
 3 import java.util.Scanner;
 4 
 5 public class Day04Equal {
 6 
 7     /**
 8      * 等腰三角形
 9         *
10        ***
11       *****
12      *******
13     *********  
14     
15     i(行数)     j(空格个数)    k(*号个数)
16     1             4               1
17     2             3              3
18     3             2 
19     4             1 
20     5             0
21      
22      i和j
23      i+j=5;
24      j<=5-i
25      
26      i和k
27      k<=2*i-1
28      */
29     public static void main(String[] args) {
30         System.out.println("您输入个数字吧！");
31         Scanner input=new Scanner(System.in);
32         int num = input.nextInt();
33         
34         for (int i = 1; i <=num; i++) {
35             //第一个循环  控制空格数量
36             for (int j = 1; j <=num-i; j++) {
37                 System.out.print(" ");
38             }
39             
40             
41             //第二个循环，控制 *  个数
42             for (int k = 1; k <=2*i-1; k++) {
43                 
44                 System.out.print("*");
45             }
46             System.out.println();
47             
48         }
49 
50     }
51 
52 }

 1 package cn.happy.shape;
 2 
 3 import java.util.Scanner;
 4 
 5 public class Day03reverseThreeShape {
 6     /*
 7      * 倒直角三角形
 8         *****
 9         ****
10         ***
11         **
12         *
13        i(行数)    j(*个数)
14        1            5
15        2            4
16        3            3
17        4            2
18        5            1
19        关系：j<=6-i
20        
21      * 
22      * 
23      */
24    public static void main(String[] args) {
25        System.out.println("爷爷，您输入一个数字吧！");
26        Scanner input=new  Scanner(System.in);
27        int num = input.nextInt();
28         for (int i = 1; i <=num; i++) {
29                //2.内层循环  每一行打印几个   *
30                 for (int j = 1; j <=num+1-i; j++) {
31                     System.out.print("*");
32                 }
33                 System.out.println();
34             }
35    }
36 }

 1 package cn.happy.shape;
 2 
 3 public class Day02triggleThreeShape {
 4 
 5     /**
 6      * 直角三角形
 7      * 
 8         *
 9         ***
10         *****
11         *******
12         *********
13         i（行数 )      j(*个数)
14         1               1
15         2               3
16         3               5
17         4               7
18         5               9
19 
20      */
21     public static void main(String[] args) {
22         //1.找行数    5行
23                 for (int i = 1; i <=5; i++) {
24                    //2.内层循环  每一行打印几个   *
25                     for (int j = 1; j <=2*i-1; j++) {
26                         System.out.print("*");
27                     }
28                     System.out.println();
29                 }
30     }
31 
32 }

 1 package cn.happy.shape;
 2 
 3 import java.util.Scanner;
 4 
 5 public class Day05LX {
 6 
 7     /**
 8      * 菱形
 9         *
10        ***
11       *****
12      *******
13       *****
14        ***
15         *
16         上半部分
17          i(行数)   j(空格数)   k(*个数)
18         1           3         1
19         2           2         3
20         3           1         5 
21         4           0         7
22         
23         i+j=4
24         j<=4-i;
25         
26         下半部分
27         i和k
28         k<=2*i-1;
29         i(行数)  j(空格)   k(*个数)
30         1         1        5
31         2         2        3
32         3         3        1
33         
34         
35         i和j
36         j<=i-1
37         
38         i和k关系
39         k<=7-2*i
40        
41         
42        
43      
44      */
45     public static void main(String[] args) {
46         System.out.println("请输入一个奇数");
47         Scanner input=new Scanner(System.in);
48         int num = input.nextInt();  //7
49         while(num%2==0){
50             System.out.println("请输入奇数");
51             num = input.nextInt();
52         }        
53         int topNum=(num+1)/2;  
54         for (int i =1; i <=topNum; i++) {
55             //控制空格
56             for (int j = 1; j <=topNum-i; j++) {
57                 System.out.print(" ");
58             }
59             for (int k = 1; k <=2*i-1; k++) {
60                 System.out.print("*");
61             }
62             System.out.println();
63         }
64         int bottomNum=num-topNum;
65         for (int i =1; i <=bottomNum; i++) {
66             //控制空格
67             for (int j = 1; j <=i; j++) {
68                 System.out.print(" ");
69             }
70             for (int k = 1; k <=num-2*i; k++) {
71                 System.out.print("*");
72             }
73             System.out.println();
74         }
75 
76     }
77 
78 }