使用for循环打印矩形和三角形、菱形、空心菱形

public class Demo3_712
{
	public static void main(String args[]){
		for(int i=1;i<=10;i++){     //控制行
			for(int j=1;j<=10;j++){	//控制列
				System.out.print("*");
			}
			System.out.println();
		}		
	}
}

public class Demo3_712
{
	public static void main(String args[]){
		for(int i=1;i<=10;i++){     //控制行
			for(int j=1;j<=i;j++){	//控制列
				System.out.print("*");
			}
			System.out.println();
		}		
	}
}

public class Demo3_712
{
	public static void main(String args[]){
		for(int i=10;i>=0;i--){     //控制行
			for(int j=1;j<=i;j++){	//控制列
				System.out.print("*");
			}
			System.out.println();
		}		
	}
}

import java.util.Scanner;

public class Demo3_712 {

	public static void main(String[] args) {
		
		System.out.println("请输入行数：");
		
		int row = new Scanner(System.in).nextInt();
		
		//循环行数
		for(int i = 1;i <= row ;i++ )
		{
			for(int a=1;a<=row-i;a++)
			{
				System.out.print(" ");
			}
			//循环列数
			for(int j = 1;j<=2*i-1;j++)
			{
				
				System.out.print("*");
			}
			//换行
			System.out.println();
		}
		
		
		for(int i = 1;i <= row ;i-- )
		{
			for(int a=1;a<=row-i;a--)
			{
				System.out.print(" ");
			}
			//循环列数
			for(int j = 1;j<=2*i-1;j--)
			{
				
				System.out.print("*");
			}
			//换行
			System.out.println();
		}
		
	}
}

import java.util.Scanner;

public class Demo3_712 {
	public static void main(String args[]) {
//		int hangshu = 11;
//		int yiban = hangshu / 2 + 1;
//		int yibanduo = hangshu / 2;
		
		Scanner sc=new Scanner(System.in);
		System.out.println("请输入行数：");
		int hangshu = sc.nextInt();
		int yiban = hangshu / 2 + 1;
		int yibanduo = hangshu / 2;
		
		System.out.println("空心菱形：");
		for (int k = 1; k <= yiban; k++) {
			for (int i = 1; i <= (yiban - k); i++) {
				System.out.print(" ");
			}
			System.out.print("*");
			for (int i = 1; i <= ((k - 2) * 2 + 1); i++) {
				System.out.print(" ");
			}
			if (k != 1) {
				System.out.print("*");
			}
			System.out.println();
		}
		for (int k = yibanduo; k >= 1; k--) {
			for (int i = 1; i <= (yiban - k); i++) {
				System.out.print(" ");
			}
			System.out.print("*");
			for (int i = 1; i <= ((k - 2) * 2 + 1); i++) {
				System.out.print(" ");
			}
			if (k != 1) {
				System.out.print("*");
			}
			System.out.println();
		}

		System.out.println("实心菱形：");
		for (int i = 1; i <= hangshu; i++) {
			if (i <= hangshu / 2 + 1) {
				for (int k = 1; k <= hangshu / 2 + 1 - i; k++) {
					System.out.print(" ");
				}
				for (int k = 1; k <= i; k++) {
					System.out.print("* ");
				}
				System.out.println();
			} else {
				for (int k = 1; k <= (i - (hangshu / 2 + 1)); k++) {
					System.out.print(" ");
				}
				for (int k = 1; k <= (2 * (hangshu / 2 + 1) - i); k++) {
					System.out.print("* ");
				}
				System.out.println();
			}
		}
	}
}