循环的实例练习

1.

package com.jredu.ch04;

import java.util.Scanner;

public class Ch24 {

public static void main(String[] args) {

// TODO Auto-generated method stub

Scanner sc=new Scanner(System.in);

System.out.println("请输入一个数字：");

int num=sc.nextInt();

for(int i=num;i>=0;i--){

for(int j =1;j<=i;j++){

System.out.print(i);//打印输出

}

System.out.println();//换行

}

for(int i=1;i<=num;i++){

for(int j =1;j<=i;j++){

System.out.print(i);

}

System.out.println();

}

}

}

2.输入某年某月某日，判断这一天是这一年的第几天？

package com.jredu.ch04;

import java.util.GregorianCalendar;

import java.util.Scanner;

public class Ch18 {

public static void main(String[] args) {

// TODO Auto-generated method stub

Scanner sc=new Scanner(System.in);

System.out.print("请输入年份：");

int y=sc.nextInt();

System.out.print("请输入月份：");

int m=sc.nextInt();

System.out.print("请输入日期：");

int d=sc.nextInt();

int d1=0;

//判断是否是闰年

GregorianCalendar gre=new GregorianCalendar();

boolean isLeapYear=gre.isLeapYear(y);

//二月份天数

int ap=isLeapYear?29:28;

switch(m){

case 1:

d1=d;

break;

case 2:

d1=31+d;

break;

case 3:

d1=31+ap+d;

break;

case 4:

d1=31+ap+31+d;

break;

case 5:

d1=31+ap+31+30+d;

break;

case 6:

d1=31+ap+31+30+31+d;

break;

case 7:

d1=31+ap+31+30+31+30+d;

break;

case 8:

d1=31+ap+31+30+31+30+31+d;

break;

case 9:

d1=31+ap+31+30+31+30+31+31+d;

break;

case 10:

d1=31+ap+31+30+31+30+31+31+30+d;

break;

case 11:

d1=31+ap+31+30+31+30+31+31+30+30+d;

break;

case 12:

d1=31+ap+31+30+31+30+31+31+30+30+31+d;

break;

default:

System.out.println("输入的月份不正确");

}

System.out.println("这一天是第"+d1+"天");

}

}

3.ATM机实例

package com.jredu.ch03;

import java.util.Scanner;

/**

* ATM机1

* @author Administrator

*

*/

public class ATM1 {

public static void main(String[] args) {

// TODO Auto-generated method stub

Scanner sc=new Scanner(System.in);

String str=null;

int sumMoney=0;

int money=0;

//最多循环三次

for(int i=0;i<3;i++) {

//输入密码

System.out.print("请输入密码:");

String pwd=sc.next();

if(!pwd.equals("111111")) {

//密码不正确

if(i==2) {

System.out.println("密码输入错误超过三次，已吞卡");

} else {

System.out.println("密码错误，还有"+(2-i)+"次机会");

}

} else {

//密码正确

//循环

//取钱

do{

System.out.println("0 请手动动输入金额");

System.out.println("1 100元");

System.out.println("2 300元");

System.out.println("3 500元");

System.out.println("4 1000元");

System.out.println("5 3000元");

System.out.println("6 5000元");

System.out.print("请输入编号：");

int code=sc.nextInt();

switch(code){

case 0:

System.out.println("请手动输入金额：");

money=sc.nextInt();

if(money>0&&money%100==0&&money<1001) {

sumMoney+=money;

System.out.println("您取了"+sumMoney+"元");

System.out.print("取款完成，是否继续（y/n）：");

} else {

System.out.println("金额有误，是否继续（y/n）");

}

break;

case 1:

money=100;

sumMoney+=money;

System.out.println("您取了元"+sumMoney+"元");

break;

case 2:

money=300;

sumMoney+=money;

System.out.println("您取了"+sumMoney+"元");

break;

case 3:

money=500;

sumMoney+=money;

System.out.println("您取了"+sumMoney+"元");

break;

case 4:

money=1000;

sumMoney+=money;

System.out.println("您取了"+sumMoney+"元");

break;

case 5:

money=3000;

sumMoney+=money;

System.out.println("您取了"+sumMoney+"元");

break;

case 6:

money=5000;

sumMoney+=money;

System.out.println("您取了"+sumMoney+"元");

break;

default:

System.out.print("输入错误，是否继续（y/n）：");

}

if(sumMoney>=20000){

sumMoney-=money;

System.out.print("取钱超额20000，是否继续（y/n）：");

}else if(sumMoney==2000){

System.out.print("您取了20000");

return;

}else{

System.out.println("是否继续（y/n）");

}

str=sc.next();

}while(str.equals("y"));

break;

}

}

System.out.println("您取了"+sumMoney+"元");

System.out.println("交易完成，请取卡");

}

}