Java 程序打印镜像下星形三角图案
在本文中，我们将学习如何在 Java 中打印镜像下星形三角形图案。
插图:
Input: number = 7
Output:
* * * * * * *
* * * * * *
* * * * *
* * * *
* * *
* *
*
*
* *
* * *
* * * *
* * * * *
* * * * * *
* * * * * * *
方法:我们可以使用循环打印镜像下星形三角图案，所以
- 用于循环
- 使用 while 循环
- 使用边做边循环
方法 1: 用于循环
例
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to print Mirror Lower Star Triangle Pattern
// Using For loop
import java.io.*;
// Main class
class GFG {
// Method
// Main driver method
public static void main(String[] args)
{
// Declare and initialize variable to
// Size of the triangle
int number = 7;
// Declaring two variables for rows and columns
int m, n;
// Outer loop 1
// Prints the first half triangle
for (m = 1; m <= number; m++) {
// Inner loop 1
for (n = 1; n < m; n++) {
// Print whitespace
System.out.print(" ");
}
// Inner loop 2
for (n = m; n <= number; n++) {
// Print star
System.out.print("*"
+ " ");
}
// Ending line after each row
System.out.println();
}
// Outer loop 2
// prints the second half triangle
for (m = number - 1; m >= 0; m--) {
// Inner loop 1
for (n = 0; n < m; n++) {
// Print whitespace
System.out.print(" ");
}
// Inner loop 2
for (n = m; n <= number - 1; n++) {
// Print star
System.out.print("*"
+ " ");
}
// Ending line after each row
System.out.println();
}
}
}
Output
* * * * * * *
* * * * * *
* * * * *
* * * *
* * *
* *
*
*
* *
* * *
* * * *
* * * * *
* * * * * *
* * * * * * *
方法 2: 使用 While 循环
例
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to Print Mirror Lower Star Triangle Pattern
// using While loop
import java.io.*;
// Main Class
class GFG {
// Main driver method
public static void main(String[] args)
{
// Declare and initialize variable to
// Size of the triangle
int number = 7;
int m = number;
int n;
// Outer loop 1
// prints the first half triangle
// ill condition holds true
while (m > 0) {
n = 0;
// Inner loop 1
// prints space until n++ < number - m is false
while (n++ < number - m) {
// print whitespace
System.out.print(" ");
}
n = 0;
// Inner loop 2
// Prints star until n++ < (m * 2) - 1 is false
while (n++ < (m * 2) - 1) {
// Print star
System.out.print("*");
}
// Ending line after each row
System.out.println();
// Decrementing by one
m--;
}
m = 1;
// Outer loop 2
// prints the second half triangle
while (m <= number) {
n = 0;
// Inner loop 1
// prints space until n++ < number - m is false
while (n++ < number - m) {
// Print whitespace
System.out.print(" ");
}
n = 0;
// Inner loop 2
// Prints star until n++ < (m * 2) - 1 is false
while (n++ < (m * 2) - 1) {
// print star
System.out.print("*");
}
// Ending line after each row
System.out.println();
m++;
}
}
}
Output
*************
***********
*********
*******
*****
***
*
*
***
*****
*******
*********
***********
*************
输出:
方法 3: 使用边做边循环
实施:
例
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to print Mirror Lower Star Triangle Pattern
// using Do-while loop
import java.io.*;
// Main class
class GFG {
// Main driver method
public static void main(String[] args)
{
// Declare variable with the
// Size of the triangle
int number = 7;
int m = number;
int n;
// Outer loop 1
// prints the first half triangle
do {
n = 0;
// Inner loop 1
// prints space until n++ < number - m is false
do {
// Print whitespaces
System.out.print(" ");
} while (n++ < number - m);
n = 0;
// Inner loop 2
// prints star until n++ < m * 2 - 2 is false
do {
// Print star
System.out.print("*");
}
while (n++ < m * 2 - 2);
System.out.println("");
}
// Condition check for do-while
while (--m > 0);
m = 1;
// Outer loop 2
// prints the second half triangle
do {
n = 0;
// Inner loop 1
// prints space until n++ < (number - m) is
// false
do {
// Print whitespace
System.out.print(" ");
} while (n++ < (number - m));
n = 0;
// Inner loop 2
// prints star until n++ < (m * 2) - 2 is false
do {
// Print star
System.out.print("*");
}
while (n++ < (m * 2) - 2);
System.out.println("");
}
// Condition check for do-while
while (++m <= number);
}
}
Output
*************
***********
*********
*******
*****
***
*
*
***
*****
*******
*********
***********
*************
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