编写循环小案例

打印等腰三角形

• 第1次推导

public class test9 {
    public static void main(String[] args) {
        // 行数
        int a = 3;

        System.out.println();
        System.out.print(" ");
        System.out.print(" ");
        System.out.print("*");

        System.out.println();
        System.out.print(" ");
        System.out.print("*");
        System.out.print("*");
        System.out.print("*");

        System.out.println();
        System.out.print("*");
        System.out.print("*");
        System.out.print("*");
        System.out.print("*");
        System.out.print("*");

    }
}

• 推导过程

public class test {
    public static void main(String[] args) {
        // 行数
        int a = 3;

        System.out.println();
        for (int i=1; i<=2; i++){
            System.out.print(" ");
        }
        for (int i=1; i<=1; i++){
            System.out.print("*");
        }

        System.out.println();
        for (int i=1; i<=1; i++){
            System.out.print(" ");
        }
        for (int i=1; i<=3; i++){
            System.out.print("*");
        }

        System.out.println();
        for (int i=1; i<=0; i++){
            System.out.print(" ");
        }
        for (int i=1; i<=5; i++){
            System.out.print("*");
        }

    }
}

• 最后

public class test {
    public static void main(String[] args) {
        // 行数
        int a=5;

        int b=1;
        for (int j=a; j>=1; j--){
            System.out.println();
            for (int i=1; i<j; i++){
                System.out.print(" ");
            }
            for (int i=1; i<=b; i++){
                System.out.print("*");
            }
            b+=2;
        }

    }
}