面向对象Java第六次作业

1.使用for 循环计算1-100的和，除了以3结尾的那些数

public class TestHello {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int i;
        int sum = 0;
        for (i = 1; i <= 100; i++) {
            if (i % 10 != 3 && i != 3)
                sum += i;
        }
        System.out.println("sum=" + sum);
    }

}

 

2.

使用二重循环输出以下图形

 

*

***

*****

*******

 

*****

****

***

**

*

public class TestHello {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        for (int i = 1; i <= 4; i++) {
            for (int j = 1; j <= 4 - i; j++)
                System.out.print(" ");

            for (int k = 1; k <= 2 * i - 1; k++)
                System.out.print("*");

            System.out.println(" ");

        }

    }
}

 

public class TestHello {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        for (int i = 1; i < 6; i++) {
            for (int j = 6 - i; j > 0; j--) {
                System.out.print("*");
            }
            System.out.println(" ");

        }

    }
}

 

 

 3.循环输入学生姓名，直到输入‘Q’程序结束。

 

import java.util.Scanner;

public class TestHello {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner input = new Scanner(System.in);
        System.out.println("请输入学生的姓名");
        String name = input.nextLine();
        for (int i = 0;; i++) {
            name = input.next();
            if (name.equals("Q")) {
                break;
            }
        }
        System.out.println("程序结束,输入完毕");
    }

}

 

 4.输入5个学生成绩，求和，当输入不合法的时候，提示输入错误重新输入

import java.util.Scanner;

public class TestHello {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner input = new Scanner(System.in);
        System.out.println("请输入学生的成绩");
        int grade, sum = 0, x;
        for (int i = 1; i <= 5;) {
            grade = input.nextInt();
            if (grade < 0 || grade > 100) {
                System.out.println("输入错误!请重新输入:");
                x = 1;
            } else {
                x = 0;
                i++;
            }
            if (x == 0) {
                sum += grade;
            }
        }
        System.out.println("学生成绩的和为" + sum);
    }

}

 

 5.计算 1+ 1/(1+2)+  1/(1+2+3)+  1/(1+2+3+4) +…………+1/(1+2+....+10)

public class TestHello {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        double sum = 0, a, b = 0;
        for (int i = 1; i <= 10; i++) {
            b += i;
            a = 1 / b;
            sum += a;
        }
        System.out.println("结果为" + sum);
    }

}

1.产生一个1-99的随机数，猜数字，若大了就提示“大了点”，若小了就提示“小了点”直到猜对为止

import java.util.Scanner;
import java.util.Random;

public class TestHello {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Random r = new Random();
        int x = r.nextInt(100);
        System.out.println(x);
        Scanner input = new Scanner(System.in);
        System.out.println("输入1-99之间数");
        int a1 = 0;
        while (true) {
            int y = input.nextInt();
            a1++;
            if (y == x) {
                System.out.println("猜对了");
                break;
            } else if (y > x) {
                System.out.println("大了点");
                continue;
            } else if (y < x) {
                System.out.println("小了点");
                continue;
            }
        }

        if (a1 >= 1 && a1 <= 3) {
            System.out.println("太棒了");
        } else if (a1 >= 5 && a1 <= 8) {
            System.out.println("一般般");
        } else if (a1 >= 5 && a1 <= 8) {
            System.out.println("太笨了");
        }

    }
}

 

  2.输入一个数，判断是不是质数（只能被1和自身整除的数是质数）

import java.util.Scanner;
import java.util.Random;

public class TestHello {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner input = new Scanner(System.in);
        System.out.println("请输入一个数");
        int a = input.nextInt();
        boolean b = true;
        for (int i = 2; i < a - 1; i++) {
            if (a % i == 0) {
                b = false;
                break;
            }
        }
        if (b) {
            System.out.println("该数是一个质数");
        } else {
            System.out.println("该数不是一个质数");
        }
    }

}

 

 3.求裴波那契数列的第20项是什么。裴波那契数列，1,1,2,3,5,8,13，21……

public class TestHello {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int x = 1;
        int y = 1;
        int z = 0;
        for (int i = 3; i < 21; i++) {
            z = x + y;
            x = y;
            y = z;
        }
        System.out.println("第20项为" + z);
    }

}