打印倒金字塔

``` java

package test ;

import java . util . Scanner ;

class file {

public static void main ( String []args ){

Scanner scan =new Scanner (System .in );

System .out . println ( " 请输入行数： " );

int n =scan . nextInt ();

for ( int hang = 1 ; hang <= n ; hang ++ ){

for ( int space = 1 ; space <= hang - 1 ; space ++ ){

//第hang行输出hang-1个空格

System .out . print ( " " );

}

for ( int star = 1 ; star <= 2 * n - 2 * hang + 1 ; star ++ ){

//第hang 行输出2*n-1 + (-2)*(hang-1)

//2*n-1 2*n-3 ...3 ,1|1,2,3...n

System .out . print ( " * " );

}

System .out . println ();

}

}

}

```