【Java3】打印三角形

1.

import java.io.*;
public class Practice {
    public static void main(String[] args){
        for(int i=0; i<5; ++i){
            for(int j=0; j<i+1; ++j){
                System.out.print('*');
            }
            System.out.println();
        }
    }
}
*
**
***
****
*****

2.

import java.io.*;
public class Practice {
    public static void main(String[] args){
        for(int i=1; i<=5; ++i){
            for(int j=1; j<=5-i; ++j){
                System.out.print(' ');
            }
            for(int k=0; k<i; ++k){
                System.out.print('*');
            }
            System.out.println();
        }
    }
}
    *
   **
  ***
 ****
*****

3.

import java.io.*;
public class Practice {
    public static void main(String[] args){
        for(int i=1; i<=5; ++i){
            for(int j=1; j<=(9-((i-1)*2+1))/2; ++j){
                System.out.print(' ');
            }
            for(int k=1; k<=(i-1)*2+1; ++k){
                System.out.print('*');
            }
            System.out.println();
        }
    }
}

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