循环

自动售票机：

import java.util.Scanner;

public class ShouPiaoJi
{
    public static void main(String[] args)
    {
        Scanner in = new Scanner(System.in);

        int balance = 0;  //余额
        while (true) {
            System.out.println("请投币：");
            //读入投币金额
            int amount = in.nextInt();

            balance = balance + amount; 

            if (balance >= 10) {
                //打印车票
                System.out.println("*******************");
                System.out.println("*  java城际铁路专线  *");
                System.out.println("*    无指定座位票    *");
                System.out.println("票价：10元");
                System.out.println("*******************");

                //计算打印找零
                System.out.println("找零：" + (balance - 10));
                balance = 0;
            }

        }
    }

}

数的位数：

package hello;

import java.util.Scanner;

public class 循环练习02数的位数
{
    public static void main(String args[])
    {
        Scanner in = new Scanner(System.in);
        int number = in.nextInt();  //判断number的位数
        int t = 0;  //计数器

        while(number>0)
        {
            number = number/10;
            t++;
        }
        System.out.println(t);
    }
}

 

//猜一个随机数的大小
package hello;
import java.util.Scanner;
import java.lang.Math;  //Math类中包含基本的数字操作，如指数、对数、平方根和三角函数。

public class 循环练习03猜数{
    public static void main(String[] args) {
        //Math.random()函数返回一个浮点数,伪随机数在范围[0,1)
        int number = (int) (Math.random() * 100 + 1); //[0,1)--->[0,100)--->[1,101)/[1,100]
        Scanner in = new Scanner(System.in);
        int t = 0;
        int a;

        do {
            a = in.nextInt();
            t++;
            if (a > number) {
                System.out.println("偏大");
            } else if (a < number) {
                System.out.println("偏小");
            } else {
                System.out.println("猜对了！你猜了" + t + "次");
            }
        }while(a!=number);
    }
}