forYezhou.java

package lab3_2;
import java.util.Scanner;

public class Lab3_2 {
	public static void main(String[] args) {
		Scanner input = new Scanner(System.in);
		System.out.print("Please enter a number(positive interger): ");
		int n = input.nextInt();
		System.out.println("Your input is:\n" + n);
		while (n < 1) {
			System.out.println("Invalid input! \nInput a positive integer: ");
			n = input.nextInt();
		}
		String spacebar = "";
		String star = "";
		int i = 0;
		for (int j = n; j>=1; j--) {
			for (i = j-1; i >= 1; i--) {
				spacebar += " ";	
			}
			System.out.print(spacebar);
			for (int k = 1; k <= 2 * (n-j)+1; k++) {
				star += "*";
			}
			System.out.print(star);
			System.out.println();
			
			spacebar = "";
			star = "";
		}
	}
}