打印5行正三角形和倒三角形

public class TestDemo {
    public static void main(String[] args) {
        //打印正三角形
        for (int i = 1; i <= 5; i++) {![](https://img2020.cnblogs.com/blog/2406104/202105/2406104-20210524230348648-800236161.png)


            for (int j = 5; j >= i; j--) {
                System.out.print(" ");
            }
            for (int j = 1;j <= i ;j++){
                System.out.print("*");
            }
            for (int j = 1; j < i; j++) {
                System.out.print("*");
            }
            System.out.println();
        }
    }
}

运行结果如下：

public class TestDemo2 {
    public static void main(String[] args) {
        //打印倒三角形
        for (int i = 1; i <= 5; i++) {
            for (int j = 1; j <= i; j++) {
                System.out.print(" ");
            }
            for (int j = 5; j >= i; j--) {
                System.out.print("*");
            }
            for (int j = 5; j > i; j--) {
                System.out.print("*");
            }
            System.out.println();
        }
    }
}

运行结果如下：