21.使用双重循环打印图形

/*
 * 打印菱形
 * */
public class PrintLX {
    public static void main(String[] args) {
        //外层循环，执行五次，每次输出一行*
        for (int i = 1; i <= 5; i++) {
            for(int j=1;j<=5-i;j++){
                System.out.print(" ");
            }
            //内层循环，执行五次，每次输出一个*
            for (int j = 1;j<=2*i-1;j++){
                System.out.print("*");
            }
            
            System.out.println();
        }
        for (int i = 1; i <= 4; i++) {
            for(int j=1;j<=i;j++){
                System.out.print(" ");
            }
            //内层循环，执行五次，每次输出一个*
            for (int j = 1;j<=7-2*(i-1);j++){
                System.out.print("*");
            }
            
            System.out.println();
        }
    }
}

/*
 * 打印平行四边形
 * */
public class PrintParallelogram {
    public static void main(String[] args) {
        //外层循环，执行五次，每次输出一行*
        for (int i = 1; i <= 5; i++) {
            for (int j = 1; j <= 5 - i; j++) {
                System.out.print(" ");
            }
            //内层循环，执行五次，每次输出一个*
            for (int j = 1;j<=5;j++){
                System.out.print("*");
            }
            System.out.println();
        }
    }
}

/*
 * 打印矩形
 * */
public class PrintRect {
    public static void main(String[] args) {
        //外层循环，执行五次，每次输出一行*
        for (int i = 1; i <= 5; i++) {
            //内层循环，执行五次，每次输出一个*
            for (int j = 1;j<=5;j++){
                System.out.print("*");
            }
            System.out.println();
        }
    }
}

/*
 * 打印等腰三角形
 * */
public class PrintSJX {
    public static void main(String[] args) {
        //外层循环，执行五次，每次输出一行*
        for (int i = 1; i <= 5; i++) {
            for(int j=1;j<=5-i;j++){
                System.out.print(" ");
            }
            //内层循环，执行五次，每次输出一个*
            for (int j = 1;j<=2*i-1;j++){
                System.out.print("*");
            }
            System.out.println();
        }
    }
}