java

public class  {
    public static void main(String[] args) {
        int size = 9;
        
        for (int i=0;i<size/2+1;i++) {
            for (int j=size/2;j>i;j--) {
                System.out.print(" ");
            }
            for (int k=0;k<2*i+1;k++) {
                System.out.print("*");
            }
            System.out.println();
        }
        //打印倒三角形
        for (int i=0;i<size/2;i++) {
            for (int j=0;j<i;j++) {
                System.out.print(" ");
            }
            for (int k=size-2*i;k>0;k--) {
                System.out.print("*");
            }
            System.out.println();
        }
    }
}