1、正等腰三角形

---

//正等腰三角形
import java.util.Scanner;

public class Demo1 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
         Scanner scan = new Scanner(System.in);
         System.out.println("输入要打印的行数：");
         int n = scan.nextInt();
         for (int i = 1; i <=n; i++) {
           //打印空格
           for (int j = 0; j < n-i; j++) {
			  System.out.print(" ");
		}
           //打印*
           for (int k = 0; k < 2*i-1; k++) {
			System.out.print("*");
		}
           //打印完一行，进行换行
           System.out.println();
	}

}
}

运行结果：

 

2、倒等腰三角形

//打印倒三角形
import java.util.Scanner;

public class Demo2 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		 Scanner scan = new Scanner(System.in);
         System.out.println("输入要打印的行数：");
         int n = scan.nextInt();
         for (int i = 1; i <=n; i++) {
        	 for (int j = 0; j <i; j++) {
				System.out.print(" ");
			}
        	 for (int k = 0; k <(2*n+1)-2*i; k++) {
				System.out.print("*");
			}
			System.out.println();
		}
	}

}

运行结果：

 3、菱形

//打印菱形
import java.util.Scanner;


public class Demo3 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		System.out.println("输入要打印菱形的行数：");
		Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        for (int i = 1; i <=n/2+1; i++) {
          for (int j = 0; j <= n/2-i; j++) {
			  System.out.print(" ");
		}
          for (int k = 0; k < 2*i-1; k++) {
			System.out.print("*");
		}
          System.out.println();
	}
        
        
         for (int i = 1; i <= n/2; i++) {
       	 for (int j = 0; j <i; j++) {
				System.out.print(" ");
			}
       	 for (int k = 0; k <(2*(n/2)+1)-2*i; k++) {
				System.out.print("*");
			}
			System.out.println();
		}
	}

}

运行结果：

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4、左下直角三角形

//左下直角三角形
import java.util.Scanner;

public class Demo4 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scan = new Scanner(System.in);
        System.out.println("输入要打印的行数：");
        int n = scan.nextInt();
        for (int i = 1; i <=n; i++) {        
          for (int j = 0; j < i; j++) {
        	  System.out.print("*");
          }
          System.out.println();
	}

}
}

运行结果：

 5、右下直角三角形

import java.util.Scanner;

//右下直角三角形
public class Demo5 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scan = new Scanner(System.in);
        System.out.println("输入要打印的行数：");
        int n = scan.nextInt();
        for (int i = 1; i <=n; i++) {
        	for (int j = 0; j <n-i; j++) {
          	  System.out.print(" ");
            }
        	for (int k = 1; k <=i; k++) {
				System.out.print("*");
			}
        	System.out.println();
        }
	}

}

运行结果：

 6、左上直角三角形

//左上直角三角形
import java.util.Scanner;

public class Demo6 {
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scan = new Scanner(System.in);
        System.out.println("输入要打印的行数：");
        int n = scan.nextInt();
        for (int i = 1; i <=n; i++) {
        	for (int j = 0; j <n+1-i; j++) {
				System.out.print("*");
			}System.out.println();
        }
	}

}

运行结果：

 7、右上直角三角形

//右上直角三角形
import java.util.Scanner;

public class Demo7 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scan = new Scanner(System.in);
        System.out.println("输入要打印的行数：");
        int n = scan.nextInt();
        for (int i = 1; i <=n; i++) {
        	for (int j = 0; j < i-1; j++) {
				System.out.print(" ");
			}
        	for (int k = 1; k <=n+1-i; k++) {
				System.out.print("*");
			}
        	System.out.println();
        }
	}

}

运行结果：

  8、数字版

public class Test2 {
	public void Triangle(int n) {
		for(int i = 1;i<=n;i++) {
			for(int j=1;j<=i;j++) {
				System.out.print(j+" ");
			}
			System.out.println();
		}
		
	}
	public static void main(String[] args) {
		// TODO Auto-generated method stub
			Test2 t = new Test2();
			t.Triangle(5);
	}

}

运行结果：