双层for循环打印三角形

实例 1

public class Demo06 { public static void main(String[] args) { //打印三角形5行 for (int i = 1; i <= 5; i++) { for (int j = 5; j >= i; j--) { System.out.print(" "); } for (int j = 1; j <= i; j++) { System.out.print("*"); } for (int j = 1; j < i; j++) { System.out.print("*"); } System.out.println(); } } }

运行结果

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

实例 2

import java.util.Scanner; public class Demo07 { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); System.out.println("请问你要几行数字"); int num = scanner.nextInt(); for (int i = 1; i <= num; i++) { for (int j = 1; j <= num - i; j++) { System.out.print(" "); } for (int j = 1; j <= (2 * i - 1); j++) { System.out.print(i); } System.out.println(); } } }

运行结果

请问你要几行数字 5 1 222 33333 4444444 555555555