Java第六周上机练习＋作业

上机练习

1.使用for循环计算1-100的和，除了以3结尾的那些数

packageaaa;

publicclass Test1 {

    /**
     * @paramargs
     */
    publicstaticvoid main(String[] args) {
        // TODO Auto-generated method stub
        int a;
        int sum = 0;
        for (a = 1; a <= 100; a++) {
            if (a % 10 != 3)
                sum += a;
        }
        System.out.println(sum);
    }

}

 

 

2.使用二重循环输出以下图形

   *

  ***

 *****

*******

packageaaa;

publicclass Test3 {

    /**
     * @paramargs
     */
    publicstaticvoid main(String[] args) {
        // TODO Auto-generated method stub
        for (int i = 1; i <= 4; i++) {
            for (int j = 0; j < 4 - i; j++) {
                System.out.print(" ");
            }
            for (int j = 1; j <= 2 * i- 1; j++) {
                System.out.print("*");
            }
            System.out.println();

        }

    }
}

 

 

*****

****

***

**

*

packageaaa;

publicclass Test2 {

    /**
     * @paramargs
     */
    publicstaticvoid main(String[] args) {
        // TODO Auto-generated method stub
        for(int i=1;i<=5;i++){
            for(int j=5;j>=i;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。

packageaaa;

importjava.util.Scanner;

publicclass Test4 {

    /**
     * @paramargs
     */
    publicstaticvoid main(String[] args) {
        // TODO Auto-generated method stub
        Scanner input = newScanner(System.in);
        while (true) {
            System.out.println("请输入学生姓名");
            String name = input.next();
            if (name.equals("Q")) {
                System.out.println("结束");
                break;
            }

        }
    }

}

 

 

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。

packageaaa;

importjava.util.Scanner;

publicclass Test5 {

    /**
     * @paramargs
     */
    publicstaticvoid main(String[] args) {
        // TODO Auto-generated method stub
        Scanner input = newScanner(System.in);
        intscore,sum=0,n;
        System.out.print("请输入学生成绩");
        for(int i=1;i<=5;){
                score=input.nextInt();
                if(score<0||score>100){
            System.out.println("输入错误！请重新输入：");
                n=1;
           }
        else{
                    n=0;
    i++;
           }
                if(n==0){
                sum+=score;    
                }
        } 
        System.out.println("和为："+sum); 

    }

}

 

 

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

package practise2;

public class Test6 {

    /**
     * @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);
    }

}

 

 作业

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”直到猜对位置

package practise2;
import java.util.Random;
import java.util.Scanner;

public class Test7 {

    /**
     * @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）

package practise2;
import java.util.Scanner;

public class Test8 {

    /**
     * @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……

package practise2;

public class Test9 {

    /**
     * @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);
    }

}