4.16

1.输出3行6列的星号

package com.ym.practise;

public class A1 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        for (int i = 1; i <= 3; i++) {
            for (int j = 1; j <= 6; j++) {
                System.out.print("*");
            }
            System.out.println();
        }
    }

}

 

 2.输出

*
**
***
****
*****

package com.ym.practise;

public class A2 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        for (int i = 1; i <= 5; i++) {
            for (int j = 1; j <= i; j++) {
                System.out.print("*");
            }
            System.out.println();
        }
    }

}

 

 3.输出九九乘法表

package com.ym.practise;

public class A3 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        for (int i = 1; i <= 9; i++) {
            for (int j = 1; j <= i; j++) {
                System.out.print(i + "*" + j + "=" + i * j + "\t");
            }
            System.out.println();
        }
    }

}

 

 4.输出

1
12
123
1234
12345
123456
1234567
12345678
123456789

package com.ym.practise;

public class A4 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        for (int i = 1; i <= 9; i++) {
            for (int j = 1; j <= i; j++) {
                System.out.print(j);
            }
            System.out.println();
        }
    }

}

 

 5.输出

1
22
333
4444
55555
666666
7777777
88888888
999999999

package com.ym.practise;

public class A5 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        for (int i = 1; i <= 9; i++) {
            for (int j = 1; j <= i; j++) {
                System.out.print(i);
            }
            System.out.println();
        }
    }

}

 

 6.输入年月日，并输出该日是该年的第几天

package com.ym.practise;

import java.util.Scanner;

public class A6 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner input = new Scanner(System.in);
        System.out.println("输入年，月，日");
        int y = input.nextInt();
        int m = input.nextInt();
        int d = input.nextInt();
        int days = 0;
        for (int i = 1; i < m; i++) {
            switch (i) {
            case 4:
            case 6:
            case 9:
            case 11:
                days += 30;
                break;
            case 2:
                if (y % 4 == 0 && y % 100 != 0 || y % 400 == 0) {
                    days += 29;
                } else {
                    days += 28;
                    break;
                }
            default:
                days += 31;
            }
        }
        days += d;
        System.out.println("是第" + days + "天");
    }

}

 

 7.输入5个数，输出最大值（循环）

package com.ym.practise;

import java.util.Scanner;

public class A7 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner input = new Scanner(System.in);
        System.out.println("输入5个数");
        int a = 0;
        int max = 0;
        for (int i = 0; i < 5; i++) {
            a = input.nextInt();
            if (i == 0) {
                max = a;
            }
            if (max < a) {
                max = a;
            }
        }
        System.out.println("最大值是" + max);
    }

}

 

 8.输入学生姓名，当输入Q时程序结束

package com.ym.practise;

import java.util.Scanner;

public class A8 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner input = new Scanner(System.in);
        System.out.println("输入学生姓名");
        String name = input.next();
        while (!name.equals("Q")) {
            name = input.next();
        }
        System.out.println("程序结束");
    }

}

 

 9.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 com.ym.practise;

import java.util.Scanner;

public class A9 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner input = new Scanner(System.in);
        int a = input.nextInt();
        boolean f = true;
        for (int i = 2; i < a; i++) {
            if (a % i == 0) {
                f = false;
                break;
            }
        }
        if (f) {
            System.out.println("是质数");
        } else {
            System.out.println("不是质数");
        }
    }

}