Java从入门到熟悉的48道练习题[完结]

july14th.2020 homework

ps：好久没写blog,所以打算写一个作业练习的系列，可以让新手更容易上手。大家加油！！废话不多说，上代码。

练习1

package july14th;

public class subject1 {

	public static void main(string[] args) {
		
		string []brand={"nike背包","adidas运动衫","李宁运动鞋","kappa外套","361°腰包"};
		for(int i=0;i<brand.length;i++){
			system.out.println(brand[i]);
		}
	}
}

练习2

package july14th;

import java.util.scanner;

public class subject2 {
	public static void main(string[] args) {
		
		double money[]=new double[5];
		scanner sc=new scanner(system.in);
		system.out.println("请输入会员本月的消费记录");
		for(int i=0;i<money.length;i++){
			system.out.println("请输入第"+(i+1)+"笔购物金额");
			money[i]=sc.nextdouble();		
		}
		
		system.out.println("");
		int sum=0;
		system.out.println("序号		"+"金额(元)");
		for(int i=0;i<money.length;i++){
			system.out.println((i+1)+"		"+money[i]);
			sum+=money[i];
		}
		system.out.println("总金额		"+sum);
	}
}

练习3

package july14th;

import java.util.arrays;
import java.util.scanner;

public class subject3 {
	
	public static void main(string[] args) {
		scanner scores=new scanner(system.in);
		system.out.println("请输入5位学员的成绩（整数）");
		int[]student=new int[5];
		for(int i=0;i<student.length;i++){
			student[i]=scores.nextint();
		}
		arrays.sort(student);
		system.out.print("学员成绩按升序排列：");
		for(int i=0;i<student.length;i++){
			system.out.print(student[i]+" ");
		}	
	}
}

练习4

package july14th;

import java.util.arrays;

public class subject4 {
	public static void main(string[] args) {
		char[]character={'a','c','u','b','e','p','f','z'};
		system.out.print("原字符序列：");
		for(int i=0;i<character.length;i++){
			system.out.print(character[i]+" ");
		}
		
		system.out.print("
升序排序后：");
		arrays.sort(character);
		for(int i=0;i<character.length;i++){
			system.out.print(character[i]+" ");
		}
		
		system.out.print("
降序排序后:");
		for(int i=0 ;i<character.length;i++){
			for(int j=character.length-1;j>=i+1;j--){
				if(character[j]>character[j-1]){
					int temp=character[j-1];
					character[j-1]=character[j];
					character[j]=(char) temp;
				}
			}
		}
		for(int i=0;i<character.length;i++){
			system.out.print(character[i]+" ");
		}
	}
}

练习5

package july14th;

import java.util.scanner;

public class subject5 {

	public static void main(string[] args) {
		scanner sc=new scanner(system.in);
		system.out.println("请输入4家店的价格");
		int price []=new int[4];
		for(int i=0;i<price.length;i++){				
			system.out.print("第"+(i+1)+"家店的价格:");
			price[i]=sc.nextint();	
		}
		
		int min=price[0];
		for(int i=0;i<price.length;i++){
			if(min>price[i]){
				min=price[i];
			}
		}
		system.out.println("最低价格是"+min);
	}
}

july20th.2020 homework

睡觉前把下午完成的作业写到blog,好困。。。要是能有个人给我点个赞我将会无比高兴！！

练习6

package july20th;

import java.util.scanner;

public class tourer {

	string name;
	int age;
	string ticket;

	public void info() {
		ticket = age <= 12 ? "免费" : "价格为：20元";
		system.out.println(name + "的年龄为：" + age + ",门票" + ticket+"
");
	}

	public static void main(string[] args) {
		scanner input = new scanner(system.in);
		int age = 0;
		string name = " ";
		for (;;) {
			tourer person = new tourer();
			if (!name.equals("n")) {
				system.out.print("请输入姓名:");
				name = input.next();
				if (name.equals("n")) {
					system.out.println("退出程序");
					break;
				}
				system.out.print("请输入年龄:");
				age = input.nextint();
				person.name = name;
				person.age = age;
				person.info();
			} else {
				break;
			}
		}
	}
}

练习7

package july20th;

import java.util.scanner;

class customer{
	int mark;
	string cardtype;
	
	public void showinfo(){		
		system.out.println("积分："+mark+",卡类型："+cardtype);
		if(mark>1000&&cardtype.equals("金卡")||
				mark>5000&&cardtype.equals("普卡")){
			system.out.println("回馈积分500分！");
		}
	}
}

public class customertest {

	public static void main(string[] args) {
		scanner input=new scanner(system.in);
		customer test=new customer();
		system.out.print("请输入您的信用卡积分：");
		test.mark=input.nextint();
		system.out.print("请输入您的信用卡类型:(金卡/普卡)");
		test.cardtype=input.next();
		test.showinfo();
	}
}

练习8

package july20th;

import java.util.scanner;

public class administrator {

	string name;
	int password;

	public void admininfo() {
		system.out.println("姓名：" + name + ",密码：" + password);
	}

	public void modifyinfo() {

	}

	public static void main(string[] args) {
		administrator admin1 = new administrator();
		admin1.name = "admin1";
		admin1.password = 111111;
		admin1.admininfo();

		administrator admin2 = new administrator();
		admin2.name = "admin2";
		admin2.password = 222222;
		admin2.admininfo();

		administrator admin3 = new administrator();
		admin3.name = "admin3";
		admin3.password = 333333;

		scanner input = new scanner(system.in);
		boolean isflag = true;
		while (isflag) {
			system.out.println("请输入用户名:");
			string name = input.next();
			system.out.println("请输入密码:");
			int password = input.nextint();
			if (admin3.name.equals("admin3") && admin3.password == password) {
				system.out.println("请输入新密码");
				password = input.nextint();
				admin3.password = password;
				system.out.println("密码修改成功，您的新密码为" + admin3.password);
				isflag = false;
			} else {
				system.out.println("用户名和密码不匹配！您没有权限更新管理员信息。");
				break;
			}
		}

	}
}

ps:以上只是我自己的解题方法，代码么，其实没有什么标准的死答案，只要写的代码能实现题目要求就好了，活学活用就好了。本菜鸡要去睡觉了zzz…晚安

july21th.2020 homework

这次的作业除了第一题写的感觉比较完美以外，另外两个题感觉做的不尽如意，不过也算是照题目要求做出来了。。。

练习9

package july21th.pro.demo1;

import java.util.scanner;

public class menu {

	scanner input = new scanner(system.in);

	public void loginmenu() { // 登录
		for (;;) {
			system.out.println("欢迎使用我行我素购物管理系统
");
			system.out.println("	1.登陆系统
");
			system.out.println("	2.退出
");
			system.out.println("***************************");
			system.out.print("请选择,输入数字：");
			int choose = input.nextint();

			if (choose == 1) {
				mainmenu();
				break;

			} else if (choose == 2) {
				system.out.println("谢谢使用");
				break;

			} else {
				system.out.println("输入错误,请重新输入!");
			}
		}
	}

	public void mainmenu() { // 主菜单
		for (;;) {
			system.out.println("我行我素购物管理系统主菜单
");
			system.out.println("***************************
");
			system.out.println("	1.客户信息管理
");
			system.out.println("	2.真情回顾
");
			system.out.println("***************************");
			system.out.print("请选择,输入数字或按0返回上一级菜单:");
			int choose = input.nextint();

			if (choose == 1) {
				customermenu();
				break;

			} else if (choose == 2) {
				sendcustmenu();
				break;

			} else if (choose == 0) {
				loginmenu();
				break;
			} else {
				system.out.println("输入错误,请重新输入!");
			}
		}
	}

	public void customermenu() { // 客戶信息管理
		for (;;) {
			system.out.println("我行我素购物管理系统主菜单>客户信息管理");
			system.out.println("***************************
");
			system.out.println("	1.添加客户
");
			system.out.println("	2.修改客户
");
			system.out.println("	3.删除客户
");
			system.out.println("***************************");
			system.out.print("请选择,输入数字或按0返回上一级菜单:");
			int choose = input.nextint();

			if (choose == 1) {
				for (;;) {
					system.out.println("执行添加客户");
					system.out.print("输入数字0返回上一级菜单:");
					int choose1 = input.nextint();
					if (choose1 == 0) {
						customermenu();
						break;
					} else {
						system.out.println("输入错误，输入数字0返回上一级菜单！");
					}
				}
				break;

			} else if (choose == 2) {
				for (;;) {
					system.out.println("执行修改客户");
					system.out.print("输入数字0返回上一级菜单:");
					int choose1 = input.nextint();
					if (choose1 == 0) {
						customermenu();
						break;
					} else {
						system.out.println("输入错误，输入数字0返回上一级菜单！");
					}
				}
				break;

			} else if (choose == 3) {
				for (;;) {
					system.out.println("执行删除客户");
					system.out.print("输入数字0返回上一级菜单:");
					int choose1 = input.nextint();
					if (choose1 == 0) {
						customermenu();
						break;
					} else {
						system.out.println("输入错误，输入数字0返回上一级菜单！");
					}
				}
				break;

			} else if (choose == 0) {
				mainmenu();
				break;

			} else {
				system.out.println("输入错误,请重新输入!");
			}
		}
	}

	public void sendcustmenu() { // 回饋顧客
		for (;;) {
			system.out.println("我行我素购物管理系统主菜单>");
			system.out.println("***************************
");
			system.out.println("	1.幸运大放送
");
			system.out.println("	2.幸运抽奖
");
			system.out.println("	3.生日问候
");
			system.out.println("***************************");
			system.out.print("请选择,输入数字或按0返回上一级菜单:");
			int choose = input.nextint();

			if (choose == 1) {
				for (;;) {
					system.out.println("执行幸运大放送");
					system.out.print("输入数字0返回上一级菜单:");
					int choose1 = input.nextint();
					if (choose1 == 0) {
						customermenu();
						break;
					} else {
						system.out.println("输入错误，输入数字0返回上一级菜单！");
					}
				}
				break;

			} else if (choose == 2) {
				for (;;) {
					system.out.println("执行幸运抽奖");
					system.out.print("输入数字0返回上一级菜单:");
					int choose1 = input.nextint();
					if (choose1 == 0) {
						customermenu();
						break;
					} else {
						system.out.println("输入错误，输入数字0返回上一级菜单！");
					}
				}
				break;

			} else if (choose == 3) {
				for (;;) {
					system.out.println("执行生日问候");
					system.out.print("输入数字0返回上一级菜单:");
					int choose1 = input.nextint();
					if (choose1 == 0) {
						customermenu();
						break;
					} else {
						system.out.println("输入错误，输入数字0返回上一级菜单！");
					}
				}
				break;

			} else if (choose == 0) {
				mainmenu();

			} else {
				system.out.println("输入错误,请重新输入!");
			}
		}
	}

}



package july21th.pro.demo1;

public class menutest {

	public static void main(string[] args) {
		menu menu=new menu();
		menu.loginmenu();
	}
}

练习10

人机猜拳（石头剪刀布）

package july21th.pro.demo2;

import java.util.scanner;

public class game {

	int computer;
	int self;

	public int selfguss() {                              // 玩家出拳
		scanner input = new scanner(system.in);
		system.out.println("请您开始出拳:1-石头、2-剪刀、3-布");
		int self = input.nextint();
		for (;;) {
			if (self == 1) {
				system.out.println("您选择出拳: 石头");
				break;

			} else if (self == 2) {
				system.out.println("您选择出拳: 剪刀");
				break;

			} else if (self == 3) {
				system.out.println("您选择出拳: 布");
				break;
			}
		}
		return self;
	}

	public int computerguss() {                          // 电脑出拳
		int computer = (int) (math.random() * 3 + 1);
		for (;;) {
			if (computer == 1) {
				system.out.println("电脑选择出拳: 石头");
				break;

			} else if (computer == 2) {
				system.out.println("电脑选择出拳: 剪刀");
				break;

			} else if (computer == 3) {
				system.out.println("电脑选择出拳: 布");
				break;
			}
		}
		return computer;

	}

	public void compare() {                               //判断谁赢
		self = selfguss();
		computer = computerguss();
		
		if (computer == 1 && self == 2 || computer == 2 && self == 3
				|| computer == 3 && self == 1) {
			system.out.println("电脑赢！！");
		} else if (computer == self) {
			system.out.println("平手！！");
		} else {
			system.out.println("恭喜，您赢了！");
		}
	}
}



package july21th.pro.demo2;

import java.util.scanner;

public class gametest {
	public static void main(string[] args) {
		game finguss=new game();		
		scanner input = new scanner(system.in);
		system.out.println("********猜拳游戏********
");
		system.out.println("请输入您的角色名");
		string name = input.next();
		system.out.println("请选择您的对手：1-孙悟空 2-孙悟饭 3-孙悟天");

		for (;;) {
			int person = input.nextint();
			if (person == 1) {
				system.out.println("***********"+name+"vs"+"孙悟空"+"***********");
				break;
			} else if (person == 2) {
				system.out.println("***********"+name+"vs"+"孙悟饭"+"***********");
				break;
			} else if (person == 3) {
				system.out.println("***********"+name+"vs"+"孙悟天"+"***********");
				break;
			} else {
				system.out.println("没有此角色，请重新输入!");
			}
		}
		
		finguss.compare();
	}
}

练习11

三个类分别是银行卡 类 ，功能类 ，测试类 。属性 用户名 密码 余额功能 类 登录 显示余额， 存 取关系 功能类中成员变量是银行卡类。

package july21th.pro.demo3;

public class bankcard {

	string name;
	int password;
	int balance;
}



package july21th.pro.demo3;

import java.util.scanner;

public class utility {
	
	bankcard card=new bankcard();
	scanner input=new scanner(system.in);
	public void login(){                                     //登录
		system.out.println("******中国建设银行atm******");
		system.out.println("1.登录");
		system.out.println("2.退出");
		system.out.print("请选择");
		
		for(;;){
			int choose=input.nextint();
			if(choose==1){
				money();
				
			}else if(choose==2){
				system.out.println("谢谢使用");
				break;
			}else{
				system.out.println("输入错误，请重新选择！");
			}
		}
	}
	 
	public void money(){                                       //主菜单
		card.name="张三";
		card.password=123456;
		system.out.println("请输入用户名：");
		string name=input.next();
		system.out.println("请输入密码：");
		int password=input.nextint();
		if(name.equals("张三")&&card.password==password){
			system.out.println("******中国建设银行atm******");
			system.out.println("1.显示余额");
			system.out.println("2.开始存钱");
			system.out.println("3.开始取钱");
			system.out.println("请选择");
			for(;;){
				int choose=input.nextint();
				if(choose==1){
					card.balance=2000;
					system.out.println("余额为："+card.balance);
					return;
				}else if(choose==2){
					addmoney();
					return;
				}else if(choose==3){
					submoney();
					return;
				}else if(choose==0){
					system.out.println("按0返回上级菜单");
					login();
				}else{
					system.out.println("选择错误，请重新输入");
				}
			}
		}else{
			system.out.println("用户名或者密码错误！！");
		}
	}
	
	public int addmoney(){                       //存钱
		system.out.println("请输入存入的钱数：");
		int money=input.nextint();
		system.out.println("您存入的钱为："+money);
		return money;
	}
	
	public int submoney(){
		system.out.println("请输入要取的钱数：");
		int money=input.nextint();
		system.out.println("您要取的钱为："+money);
		return money;
	}
}



package july21th.pro.demo3;

public class bankcardtest {

	public static void main(string[] args) {
		utility uti=new utility();
		uti.login();
	}
}

不知道什么时候才能恢复线下课啊，该死的新冠，2020，我可太难了啊！！

july24th.2020 homework

这次作业感觉完成的比较满意，虽然完成慢一点。。

练习12

自定义方法 ：两个 int参数 ， 返回 随机数int。

package july24th.demo1;

import java.util.scanner;

public class randomtest {
	public static void main(string[] args) {
		random num = new random();
		scanner input = new scanner(system.in);
		system.out.println("请输入第一个整数：");
		int a = input.nextint();
		system.out.println("请输入第二个整数：");
		int b = input.nextint();
		system.out.println(num.getrandom(a, b));
	}
}

class random {
	public int getrandom(int a, int b) {
		int ran = (int) (math.random() * (b - a + 1) + a);
		return ran;
	}
}

任意两个整数之间的随机数：

(int)(math.random()*(b-a+1)+a;

练习13

自定义方法 ，两个参数1 string[] 2string name 返回 找到的下标。

package july24th.demo2;

public class nameindex {

	public int getindex(string[] arr, string name) {
		for (int i = 0; i < arr.length; i++) {
			if (name.equals(arr[i])) {
				return i;
			}	
		}
		return -1;
	}
}



package july24th.demo2;

import java.util.scanner;

public class nameindextest {
	public static void main(string[] args) {
		scanner input = new scanner(system.in);
		nameindex index = new nameindex();
		string[] name = new string[] { "jack", "lilly", "tom", "benz" };
		for (string i : name) {
			system.out.print(i + " ");
		}
		system.out.println("
");
		system.out.println("请输入你要查找的名字");
		string person = input.next();
		int index1 = index.getindex(name, person);
		if (index1 >= 0) {
			system.out.println("恭喜您，找到了，在第" + (index1 + 1) + "位");
		} else {
			system.out.println("很遗憾，数据库没有这个人！");
		}
	}
}

练习14

atm系统,登录，显示余额、存钱、取钱、退出功能。

package july24th.demo3;

public class bank {

	int account;
	int password;
	double balance;
}



package july24th.demo3;

import java.util.scanner;

public class atm {

	scanner input = new scanner(system.in);
	bank b = new bank();

	public void info() { // 初始化
		b.account = 888888;
		b.password = 123456;
		b.balance = 500;
	}

	public void main() {
		system.out.println("1.显示余额");
		system.out.println("2.我要存钱");
		system.out.println("3.我要取钱");
		system.out.println("4.退出");
		for (;;) {
			system.out.println("请选择功能：");
			int choose = input.nextint();
			if (choose == 1) {
				showmoney();
			} else if (choose == 2) {
				system.out.println("请输入要存入的钱");
				deposit(input.nextdouble());
			} else if (choose == 3) {
				system.out.println("请输入要取出的钱");
				withdraw(input.nextdouble());
			} else if (choose == 4) {
				system.out.println("谢谢使用");
				break;
			} else {
				system.out.println("没有此选项，请重新输入!");
			}
		}
	}

	public boolean login(int acc, int pass) { // 校验账户密码
		if (acc == b.account && pass == b.password) {
			return true;
		}
		return false;
	}

	public void showmoney() { // 账户余额
		system.out.println("您的余额为" + b.balance);
	}

	public void deposit(double amount) { // 存钱
		if (b.balance > 0) {
			b.balance += amount;
		}
		system.out.println("存钱成功，您当前余额为" + b.balance);
	}

	public void withdraw(double amount) { // 取钱
		if (b.balance < amount) {
			system.out.println("对不起，您的余额不足！");
		} else {
			b.balance -= amount;
			system.out.println("取钱成功，您当前余额为" + b.balance);
		}
	}

}



package july24th.demo3;

import java.util.scanner;

public class atmtest {

	public static void main(string[] args) {
		system.out.println("**********中国建设银行**********");
		scanner input = new scanner(system.in);
		atm a = new atm();
		a.info();
		for (int i = 4; i > 0; i--) {
			system.out.println("请输入账号");
			int account = input.nextint();
			system.out.println("请输入密码");
			int password = input.nextint();
			boolean num = a.login(account, password);
			if (num) {
				system.out.println("登录成功");
				a.main();
				break;
			} else {
				system.out.println("账号或密码错误" + "您还有" + (i - 1) + "次机会");
			}
		}

	}
}

练习15

自定义数组 ，参数 1 数组 2 字符串 返回数组 int

参数1 无序数组 ， 根据参数2 ，方法中 判断 返回升序或降序后的数组

package july24th.demo4;

import java.util.scanner;

public class bubbletest {

	public static void main(string[] args) {
		bubble test = new bubble();
		int[] ron = new int[10];
		for (int i = 0; i < ron.length; i++) {
			ron[i] = (int) (math.random() * 100 + 1);
		}
		for (int i : ron) {
			system.out.print(i + " ");
		}
		scanner input = new scanner(system.in);
		system.out.println(" ");
		for (;;) {
			system.out.println("请问您是升序还是降序？(up/down)");
			int[] arr = ron;
			test.sort(arr, input.next());
			for (int i : arr) {
				system.out.print(i + " ");
			}
			system.out.println(" ");
			system.out.println("请问是否继续(y/n)");
			string s = input.next();
			if (s.equals("y")) {

			} else {
				system.out.println("谢谢使用！");
				break;
				
			}
		}
	}
}

class bubble {
	public int[] sort(int[] arr, string choose) {
		if (choose.equals("up")) {
			for (int i = 0; i < arr.length - 1; i++) {
				for (int j = 0; j < arr.length - i - 1; j++) {
					if (arr[j] > arr[j + 1]) {
						int temp = arr[j];
						arr[j] = arr[j + 1];
						arr[j + 1] = temp;
					}
				}
			}
			return arr;
		} else {
			for (int i = 0; i < arr.length - 1; i++) {
				for (int j = 0; j < arr.length - i - 1; j++) {
					if (arr[j] < arr[j + 1]) {
						int temp = arr[j];
						arr[j] = arr[j + 1];
						arr[j + 1] = temp;
					}
				}
			}
			return arr;
		}
	}
}

end.

july27th.2020 homework

练习16

package july27th.demo2;

public class excelle {

	private string type;
	private string id;
	
	public excelle(string id,string type){
		this.id=id;
		this.type=type;
	}

	public string gettype() {
		return type;
	}

	public string getid() {
		return id;
	}
	
	
}



package july27th.demo2;

public class regal {

	private string type;
	private string id;
	
	public regal(string id,string type){
		this.id=id;
		this.type=type;
	}

	public string gettype() {
		return type;
	}

	public string getid() {
		return id;
	}
	
}



 package july27th.demo2;

public class seller {

	private string name;

	public string getname() {
		return name;
	}

	public void setname(string name) {
		this.name = name;
	}
	
	public void sell(excelle car){
		system.out.println(car.getid()+" "+car.gettype());
	}
	
	public void sell(regal car){
		system.out.println(car.getid()+" "+car.gettype());
	}
	
	

	public void sell(excelle car,int num) {
		system.out.println(name+" "+num+"辆"+"编号："+car.getid()+"品牌："+car.gettype());
	}


	
}



package july27th.demo2;

public class test {

	public static void main(string[] args) {
		seller name=new seller();
		name.setname("jack");
		excelle e=new excelle("1","凯越");
		name.sell(e, 100);
		name.sell(e);
	}
}

练习17

package july27th.demo1;

public class dog {

	string nickname;
	private int health;
	int love;
	
	public dog(){
		
	}

	public dog(string nickname, int health, int love) {
		this.nickname = nickname;
		this.health = health;
		this.love = love;
	}
	
	public void sethealth(int health){
		if(health<=100&&health>=0){
			this.health=health;
		}else{
			this.health=50;
		}
	}
	
	public int gethealth(){
		return health;
	}
	
	public void print() {
		system.out.println("我的名字叫" + nickname + "，健康值是" + health + "，和主人的亲密度是"
				+ love );
	}
}



package july27th.demo1;

public class penguin {
	string nickname;
	private int health;
	int love;
	
	public penguin(){
		
	}

	public  penguin(string nickname, int health, int love) {
		this.nickname = nickname;
		this.health = health;
		this.love = love;
	}
	
	public void sethealth(int health){
		if(health<=100&&health>=0){
			this.health=health;
		}else{
			this.health=50;
		}
	}
	
	public int gethealth(){
		return health;
	}
	
	public void print() {
		system.out.println("我的名字叫" + nickname + "，健康值是" + health + "，和主人的亲密度是"
				+ love );
	}


}



package july27th.demo1;

import java.util.scanner;

public class petstest {

	public static void main(string[] args) {
		system.out.println("欢迎来到宠物店");
		scanner input=new scanner(system.in);
		system.out.print("请输入要领养的宠物名字:");
        string name=input.next();
		system.out.println("请选择要领养的宠物类型：(1、狗狗 2、企鹅)");
		int choose=input.nextint();
		if(choose==1){
			system.out.println("请选择狗狗的品种：(1、聪明的拉布拉多犬 2、酷酷的雪瑞纳)");
			dog d=new dog();
			int n=input.nextint();
			d.sethealth(-50);
			dog d2=new dog(name,d.gethealth(),0);
			string s=n==1? "聪明的拉布拉多犬":"酷酷的雪瑞纳";
			
			system.out.println("宠物的自白：");
			system.out.println("我的名字叫" + name + "，健康值是" + d2.gethealth() + "，和主人的亲密度是"
					+ d.love + "，我是一只" + s);
		}else if(choose==2){
			system.out.println("请选择企鹅的性别：(1、q仔2、q妹)");
			penguin d=new penguin();
			int f=input.nextint();
			d.sethealth(-50);
			penguin d2=new penguin(name,d.gethealth(),0);
			string s=f==1? "q仔":"q妹";
			
			system.out.println("宠物的自白：");
			system.out.println("我的名字叫" + name + "，健康值是" + d2.gethealth() + "，和主人的亲密度是"
					+ d.love + "，性别是" + s);
		}else{
			system.out.println("输入错误，请重新输入");
		}
		
	    
	}
}

end.

july28th.2020 homework

练习18

要求 ：
1 父类水果类 没有属性， 有一个抽象方法 （结出水果,无返回，无参数）
2 香蕉 子类 重写结出水果 输出结出一个香蕉
3 苹果子类 重写结出水果 输出结出一个苹果
4 测试类 new 两个子类 调用结出的方法

package july28th.demo1;

public abstract class fruit {

	public abstract void fruit();
			
}

class banana extends fruit{
	@override
	public void fruit() {
		// todo auto-generated method stub
		system.out.println("结出一个香蕉");
	}
}

class apple extends fruit{
	@override
	public void fruit() {
		// todo auto-generated method stub
		system.out.println("结出一个苹果");
	}
}


package july28th.demo1;

public class fruittest {
	
	public static void main(string[] args) {
		banana b=new banana();
		b.fruit();
		
		apple a=new apple();
		a.fruit();
	}
}

练习19

要求 ：
1 父类披萨类 没有属性， 有一个生成披萨的方法 （生成披萨,string返回，无参数）
2 芝士披萨 子类 重写生成披萨的方法 输出结出一个芝士披萨
3 牛肉披萨 子类 重写生成披萨的方法 输出结出一个牛肉披萨
4 测试类 new 两个子类 调用结出的方法 注意有返回类型

package july28th.demo2;

public class pizza {

	public string pizza(){
		string pizza="披萨";
		system.out.println(pizza);
		return pizza;
	}
}

class cheesepizza extends pizza{
	@override
	public string pizza() {
		// todo auto-generated method stub
		string pizza="芝士披萨";
		return pizza;
	}
}

class beefpizza extends pizza{
	@override
	public string pizza() {
		// todo auto-generated method stub
		string pizza="牛肉披萨";
		return pizza;
	}
}


package july28th.demo2;

public class pizzatest {

	public static void main(string[] args) {
		cheesepizza cheese=new cheesepizza();
		system.out.println("做一个"+cheese.pizza());
		
		beefpizza beef=new beefpizza();
		system.out.println("做一个"+beef.pizza());
	}
}

练习20

package july28th.demo3;

public abstract class motovehicle {

	int number;
	string brand;
	string color;
	double mileage;
	
	public abstract void calcrent(int days);
}

class car extends motovehicle {

	string type;

	public car(int number, string type) {
		this.number = number;
		this.type = type;
	}

	@override
	public void calcrent(int days) {
		// todo auto-generated method stub
		if (type.equals("别克商务舱gl8")) {
			system.out.println("租金是：" + days * 600+"元");
		} else if (type.equals("宝马550i")) {
			system.out.println("租金是：" + days * 500+"元");
		} else if (type.equals("别克林荫大道")) {
			system.out.println("租金是：" + days * 300+"元");
		} else {
			system.out.println("本公司无此车！");
		}
	}

}

class bus extends motovehicle {

	int seatcount;

	public bus(int number, int seatcount) {
		this.number=number;
		this.seatcount=seatcount;
	}

	@override
	public void calcrent(int days) {
		// todo auto-generated method stub
		if(seatcount>=16){
			system.out.println("租金是："+days*1500+"元");
		}else{
			system.out.println("租金是："+days*800+"元");
		}

	}
}


package july28th.demo3;

import java.util.scanner;

public class motovehicletest {

	public static void main(string[] args) {
		for(;;){
			system.out.println(" 拓海租车行
");
			system.out.println("************************");
			system.out.println("轿车：别克商务舱gl8(￥600/天)、宝马550i(￥500/天)、" +
					"别克林荫大道(￥300/天)
");
			system.out.println("客车：16座以上(￥1500/天)、16座以下(￥800/天)
");
			scanner input=new scanner(system.in);
			system.out.println("请问您要租什么类型的车？(1.轿车、2.客车)");
			int choose=input.nextint();
			if(choose==1){
				system.out.println("您要租的是桥车，请输入您要租的车具体型号");
				string type=input.next();
				car c=new car(666,type);			
				system.out.println("请输入您要租的天数");
				int num=input.nextint();
				system.out.print("您要租的是："+type+" "+"车牌号是"+c.number+" ");
				c.calcrent(num);
				break;
			}else if(choose==2){
				system.out.println("您要租的是客车，请问您需要多少座位的客车？");
				int number=input.nextint();
				bus b=new bus(888,number);
				system.out.println("请输入您要租的天数");
				int day=input.nextint();
				system.out.print("您要租的是："+number+"座客车"+" "+"车牌号是"+b.number+" ");
				b.calcrent(day);
				break;
			}else{
				system.out.println("输入错误，请重新输入");
			}
		}
		
	}
}

end.

july31th.2020 homework

练习21

要求：
1.国家 父类
2.中国 说汉语
3.美国 说英语
4.人类 说话 参数 是多态

package july31th.demo2;

public class nation {

	public void speak(){
		system.out.println("地球人会说话！");
	}
}

class china extends nation{
	@override
	public void speak() {
		// todo auto-generated method stub
		system.out.println("中国人说汉语");
	}
}

class american extends nation{
	@override
	public void speak() {
		// todo auto-generated method stub
		system.out.println("美国人说英语");
	}
}

class person{
	public void speak(nation s){
		s.speak();
	}
}


package july31th.demo2;

public class nationtest {

	public static void main(string[] args) {
		person p=new person();
		china c=new china();
		american a=new american();
		p.speak(c);
		//p.speak(a);
	}
}

练习22

要求：
1.果树
2.苹果树
3.香蕉树
4.超市 参数 字符串 返回类型多态 相应的水果

package july31th.demo3;

public class supermarket {

	public tree gettree(string s){
		tree n=null;
		if(s.equals("苹果")){
			n=new appletree();
		}else if(s.equals("香蕉")){
			n=new bananatree();
		}
		return n;
	}
}

class tree{
	public void show(){
		system.out.println("树木");
	}
}

class appletree extends tree{
	@override
	public void show() {
		// todo auto-generated method stub
		system.out.println("苹果");
	}
}

class bananatree extends tree{
	@override
	public void show() {
		// todo auto-generated method stub
		system.out.println("香蕉");
	}
}




package july31th.demo3;

public class supermarkettest {

	public static void main(string[] args) {
		supermarket market=new supermarket();
		string s="苹果";
		tree n=market.gettree(s);
		n.show();	
	}
}

end.

auguest3rd.2020 homework

练习23

1 汽车父类（属性：汽车名称，车牌；方法：显示所有信息）
2 租金接口 （计算租金方法 返回double 方法名(int day租借天数)）
3 客车类 （自己属性座位数） 继承汽车 实现租金（重写租金方法 方法中座位数_day） 1 day=500 * 座位数
4 货车类 （自己属性载重量） 继承汽车 实现租金（重写租金方法 方法中载重量_day） 1 day=1000* 多少吨
5 测试类 测试两种车

package august3rd.demo1;

public class car {

	string brand;
	string num;

	public void info() {
		system.out.println("品牌是：" + brand + "车牌是：" + num);
	}
}



package august3rd.demo1;

public interface rental {

	double getmoney(int day);
}




package august3rd.demo1;

public class bus extends car implements rental {

	int seatnum;
	@override
	public double getmoney(int day) {
		// todo auto-generated method stub
		double money=day*500;
		return money;
	}

}



package august3rd.demo1;

public class truckload extends car implements rental {

	int weight;

	@override
	public double getmoney(int day) {
		// todo auto-generated method stub
		double money=day*1000;
		return money;
	}
}



package august3rd.demo1;

import java.util.scanner;

public class test {

	public static void main(string[] args) {
		scanner input=new scanner(system.in);
		bus test=new bus();
		system.out.println("请输入所需客车的座位数");
		test.seatnum=input.nextint();
		system.out.println("请输入租车天数");
		int num=input.nextint();
		system.out.println(test.getmoney(num)+"元");
		
		system.out.println("******************");
		truckload t=new truckload();
		system.out.println("请输入所需货车的载重");
		t.weight=input.nextint();
		system.out.println("请输入租车天数");
		int day=input.nextint();
		system.out.println(t.getmoney(day)+"元");
	}
}

练习24

package august3rd.demo2;

public class handset {

	string brand;
	string type;

	public void sendinfo() {
		system.out.println("可以发短信");
	}

	public void call() {
		system.out.println("可以打电话");
	}

	public void info() {
		system.out.println("手机品牌是：" + brand + "型号是：" + type);
	}

}



package august3rd.demo2;

public interface playwiring {

	void paly(string content);
}



package august3rd.demo2;

public interface takephoto {

	void takephoto();
}



package august3rd.demo2;

public interface network {

	void net();
}



package august3rd.demo2;

public class commonhandset extends handset implements playwiring {

	@override
	public void paly(string content) {
		// todo auto-generated method stub
		system.out.println("可以播放" + content);
	}

}



package august3rd.demo2;

public class smartphone extends handset implements network, takephoto,
		playwiring {

	@override
	public void paly(string content) {
		system.out.println("可以播放" + content);

	}

	@override
	public void takephoto() {
		// todo auto-generated method stub
		system.out.println("可以照像");
	}

	@override
	public void net() {
		// todo auto-generated method stub
		system.out.println("可以上网");
	}

}



package august3rd.demo2;

public class test {

	public static void main(string[] args) {
		commonhandset test=new commonhandset();
		system.out.println("功能机");
		test.brand="nokia";
		test.type="5230";
		test.info();
		test.paly("音乐");
		test.sendinfo();
		test.call();
		system.out.println("**************************");
		system.out.println("智能机");
		
		smartphone smart=new smartphone();
		smart.brand="apple";
		smart.type="iphone8 plus";
		smart.info();
		smart.net();
		smart.paly("视频");
		smart.takephoto();
		smart.sendinfo();
		smart.call();
	}
	
}

end.

august4th.2020 homework

练习25

package august4th.demo1;

import java.util.inputmismatchexception;
import java.util.scanner;

import org.apache.log4j.logger;

class subject {

	int firstnum;
	int secondnum;

	public void getnum(int num) throws exception {
		if (num == 0) {
			throw new exception("出现错误，被除数和除数必须是整数，除数不能为零。");
		}
	}
}

public class subjecttest {
	public static logger log = logger.getlogger("");

	public static void main(string[] args) {
		scanner input = new scanner(system.in);
		subject test = new subject();
		system.out.print("请输入被除数:");
		test.firstnum = input.nextint();
		log.debug("输入被除数:"+test.firstnum);
		system.out.print("请输入除数:");
		test.secondnum = input.nextint();
		log.debug("输入除数:"+test.secondnum);
		if(test.secondnum==0){
			log.error("/ by zero");
		}
		try {
			test.getnum(test.secondnum);
			
		} catch (exception e) {
			// todo auto-generated catch block
			e.printstacktrace();
		}
		system.out.println(test.firstnum / test.secondnum);

		log.debug("输出运算结果："+test.firstnum +"/"+ test.secondnum+"="+(test.firstnum / test.secondnum));
	}
}

练习26

package august4th.demo2;

public class animal {

	private string name;
	private int legnum;

	public animal(string name, int legnum) {
		this.name = name;
		this.legnum = legnum;
	}

	public string getname() {
		return name;
	}

	public int getlegnum() {
		return legnum;
	}

	public void shout() {
		system.out.println("动物会叫！");
	}

}

class cat extends animal {

	public cat(string name, int legnum) {
		super(name, legnum);
		// todo auto-generated constructor stub
	}

	@override
	public void shout() {
		// todo auto-generated method stub
		system.out.println("猫咪喵喵叫!");
	}

}

class duck extends animal {

	public duck(string name, int legnum) {
		super(name, legnum);
		// todo auto-generated constructor stub
	}

	@override
	public void shout() {
		// todo auto-generated method stub
		system.out.println("鸭子嘎嘎叫!");
	}

}



package august4th.demo2;

public class animaltest {

	public static void main(string[] args) {
		animal cat=new cat("coco", 4);
		
		system.out.print("昵称："+cat.getname()+"有");
		system.out.println(cat.getlegnum()+"条腿");
		cat.shout();
		
		
		system.out.println("**********************");
		animal duck=new duck("二丫",2);
		system.out.print("昵称："+duck.getname()+"有");
		system.out.println(duck.getlegnum()+"条腿");
		duck.shout();
	}
	
}

练习27

package august4th.demo3;

public class animal {

	private string name;

	public animal(string name) {
		this.name = name;
	}

	public void shout(){
		system.out.println("动物会叫！");
	}
}

class cat extends animal implements terrestrial {

	private int legnum;

	public cat(string name,int legnum) {
		super(name);
		this.legnum=legnum;
		// todo auto-generated constructor stub
	}

	@override
	public void shout() {
		// todo auto-generated method stub
		system.out.println("猫咪喵喵叫！");
	}

	@override
	public int getlegnum() {
		// todo auto-generated method stub
		return this.legnum;
	}

}

class duck extends animal implements terrestrial{

	private int legnum;
		
	public duck(string name,int legnum) {
		super(name);
		this.legnum=legnum;
		// todo auto-generated constructor stub
	}

	@override
	public void shout() {
		// todo auto-generated method stub
		system.out.println("鸭子嘎嘎叫");
	}

	@override
	public int getlegnum() {
		// todo auto-generated method stub
		return this.legnum;
	}


}

class dolphin extends animal{

	public dolphin(string name) {
		super(name);
		// todo auto-generated constructor stub
	}
	@override
	public void shout() {
		// todo auto-generated method stub
		system.out.println("海豚音");
	}
}



package august4th.demo3;

public interface terrestrial {
 
	int getlegnum();
}



package august4th.demo3;

public class animaltest {

	public static void main(string[] args) {
		cat cat=new cat("皮卡丘",4);

		system.out.println(cat.getlegnum());
		cat.shout();
		
		duck duck=new duck("唐老鸭", 2);
		system.out.println(duck.getlegnum());
		duck.shout();
		
		dolphin d=new dolphin("tt");
		d.shout();
	}
}

end.

august7th.2020 homework

练习28

新建一个list 对象 ，学生类姓名和分数属性 ，新建5个对象，显示所有学生信息。

package august7th;

import java.util.arraylist;
import java.util.list;

public class studenttest {

	public static void main(string[] args) {
		list list=new arraylist();
		student stu=new student("小明",78);
		student stu2=new student("小花",90);
		student stu3=new student("小刚",23);
		student stu4=new student("小东",50);
		student stu5=new student("小花",44);
		list.add(stu);
		list.add(stu2);
		list.add(stu3);
		list.add(stu4);
		list.add(stu5);
		
//		for(object o:list){                 for each遍历
//			student student=(student)o;
//			student.info();
//		}
		
		for(int i=0;i<list.size();i++){
			student student=(student) list.get(i);
			student.info();
		}
		
	}
}

class student{
	string name;
	int scores;
	
	public student(string name,int scores){
		this.name=name;
		this.scores=scores;
	}
	
	public void info(){
		system.out.println("姓名："+name+"		"+"年龄："+scores);
	}
}

end

august11th.2020 homework

练习29

第一个类 两个构造方法 无参数和两个参数 set/get

package august11th;

import java.util.arraylist;
import java.util.list;

public class penguintest {

	public static void main(string[] args) {
		list list=new arraylist();
		penguin p1=new penguin("东东 ，健康度：",98);
		penguin p2=new penguin("南南 ，健康度：",96);
		penguin p3=new penguin("西西 ，健康度：",99);
		penguin p4=new penguin("北北， 健康度：",95);
		list.add(p1);
		list.add(p2);
		list.add(p3);
		list.add(p4);
		system.out.println("一共"+list.size()+"只企鹅");
		for(object o:list){
			penguin p=(penguin)o;
			system.out.println(p);
		}
		system.out.println("删除第一个企鹅的信息
");
		list.remove(0);
		for(object o:list){
			penguin p=(penguin)o;
			system.out.println(p);
		}
		
		system.out.println("删除西西的信息
");
		list.remove(p3);
		for(object o:list){
			penguin p=(penguin)o;
			system.out.println(p);
		}
	}
}

class penguin {
	private string name = "大白";
	int health = 100;
	private int love = 0;
	string sex = "q仔";

	public string getname() {
		return name;
	}

	public void setname(string name) {
		this.name = name;
	}

	public int getlove() {
		return love;
	}

	public void setlove(int love) {
		this.love = love;
	}

	public penguin(string name, int love) {
		super();
		this.name = name;
		this.love = love;
	}

	public penguin() {
		super();
	}

	@override
	public string tostring() {
		// todo auto-generated method stub
		return name+love;
	}
	
	

}

练习30

package august11th;

import java.util.hashmap;
import java.util.map;
import java.util.set;

public class dogtest {

	public static void main(string[] args) {
//		dog ou=new dog("欧欧","雪纳瑞");
//		dog ya=new dog("亚亚","拉布拉多"); 
//		dog mei=new dog("美美","柯基");
//		dog fei=new dog("菲菲","柴犬");
		map<string,string> dog=new hashmap<string,string>();
		dog.put("欧欧","雪纳瑞");            //dog.put(key,value)
		dog.put("亚亚","拉布拉多");
		dog.put("美美","柯基");
		dog.put("菲菲","柴犬");
		if(dog.containskey("欧欧")){         //判断是否有key"欧欧"
			dog d=new dog("欧欧","拉布拉多");
			system.out.println(d.getname()+"		"+d.getstrain());
		}else{
			set set=dog.keyset();
			for(object o:set){		
				system.out.println(set);
			}
		}
		
	}
}

class dog {
	private string name;
	private int health;
	private int love;
	private string strain;

	public string getname() {
		return name;
	}

	public void setname(string name) {
		this.name = name;
	}

	public int gethealth() {
		return health;
	}

	public void sethealth(int health) {
		this.health = health;
	}

	public int getlove() {
		return love;
	}

	public void setlove(int love) {
		this.love = love;
	}

	public string getstrain() {
		return strain;
	}

	public void setstrain(string strain) {
		this.strain = strain;
	}

	public dog(string name, string strain) {
		super();
		this.name = name;
		this.strain = strain;
	}
	
	public dog(){
		
	}

}

练习31

package august11th;

import java.util.hashmap;
import java.util.iterator;
import java.util.map;

public class rabbittest {

	public static void main(string[] args) {
		rabbit r1 = new rabbit("欧欧", "公");
		rabbit r2 = new rabbit("亚亚", "母");
		rabbit r3 = new rabbit("美美", "公");
		rabbit r4 = new rabbit("菲菲", "母");
		map<string, string> rabbit = new hashmap<string, string>();
		rabbit.put(r1.getname(), r1.getsex()); // dog.put(key,value)
		rabbit.put(r2.getname(), r2.getsex());
		rabbit.put(r3.getname(), r3.getsex());
		rabbit.put(r4.getname(), r4.getsex());
		
		for(string n:rabbit.keyset()){
			system.out.println(n);
		}
		
		system.out.println("*****************");
		iterator it = rabbit.keyset().iterator();
		while (it.hasnext()) {
			object s = it.next();
			system.out.println(s);
		}
		
	}
}

class rabbit {
	private string name = "大白";
	int health = 100;
	private int love = 0;
	string sex = "公";

	public string getname() {
		return name;
	}

	public void setname(string name) {
		this.name = name;
	}

	public string getsex() {
		return sex;
	}

	public void setsex(string sex) {
		this.sex = sex;
	}

	public rabbit(string name, string sex) {
		super();
		this.name = name;
		this.sex = sex;
	}

	public rabbit() {
		super();
	}

	@override
	public string tostring() {
		// todo auto-generated method stub
		return name + love;
	}
}

end

august12th.2020 homework

练习32

package august12th;

import java.util.scanner;

public class subject {

	public static void main(string[] args) {
		for (;;) {
			scanner input = new scanner(system.in);
			system.out.print("请输入用户名:");
			input.next();
			system.out.print("请输入密码：");
			int l = input.nextint();
			way w = new way();
			w.getlength(l);
			integer it=l;
			string s=it.tostring();
			if(s.length()==6){
				break;
			}
		}

	}
}

class way {
	public void getlength(int l) {
		integer it = l;
		string s = it.tostring();
		s.length();
		if (s.length() < 6) {
			system.out.println("密码长度不小于6位！请重新输入！");
		} else if (s.length() > 6) {
			system.out.println("密码长度不能大于6位！请重新输入！");
		} else {
			system.out.println("注册成功！");
		}
	}
}

练习33

package august12th;

import java.util.scanner;

public class subject2 {

	public static void main(string[] args) {

		for (;;) {
			scanner input = new scanner(system.in);
			system.out.print("请输入用户名:");
			string s = input.next();
			system.out.print("请输入密码:");
			int n = input.nextint();
			if (s.equalsignorecase("tom")) {
				system.out.println("用户名正确，登录成功！");
				break;
			} else {
				system.out.println("用户名错误！");
			}

		}

	}
}

练习34

package august12th;

import java.util.scanner;

public class subject3 {

	public static void main(string[] args) {
		system.out.println("***欢迎进入注册系统***
");
		for (;;) {
			scanner input = new scanner(system.in);
			system.out.print("请输入用户名：");
			string s = input.next();
			system.out.print("请输入密码:");
			int l = input.nextint();
			until t = new until();
			t.getlength(s, l);
			integer it = l;
			string n = it.tostring();

			if (s.length() >= 3 && n.length() >= 6) {
				system.out.print("请再次输入密码：");
				int j = input.nextint();
				t.password(l, j);
				if (l == j) {
					break;
				}

			}

		}
	}
}

class until {
	public void getlength(string s, int l) {
		integer it = l;
		string n = it.tostring();
		if (s.length() < 3 || n.length() < 6) {
			system.out.println("用户名长度不能小于3，密码长度不能小于6");
		}
	}

	public void password(int i, int j) {
		if (i == j) {
			system.out.println("注册册成功，请牢记用户名和密码");
		} else {
			system.out.println("两次输入的密码不相同，请重新输入！");
		}
	}
}

练习35

package august12th;

import java.util.scanner;

public class subject4 {

	public static void main(string[] args) {
		for (;;) {
			scanner input = new scanner(system.in);
			system.out.println("---欢迎进入作业提交系统---");
			system.out.print("请输入java文件名：");
			string s = input.next();
			system.out.print("请输入邮箱：");
			string n = input.next();
			way2 test = new way2();
			test.getinfo(s, n);
			int n1 = n.indexof('.');
			int n2 = n.indexof('@');
			if (s.endswith(".java") && n1 > n2) {
				break;
			} else {
				system.out.println("e-mail无效。
作业提交失败！");
			}
		}
	}
}

class way2 {
	public void getinfo(string s, string t) {
		int n1 = t.indexof('.');
		int n2 = t.indexof('@');
		if (s.endswith(".java") && n1 > n2) {
			system.out.println("作业提交成功！");
		}
	}
}

练习36

package august12th;

public class subject5 {

	public static void main(string[] args) {
		string word="hello,  ";
		word=word.trim();  //删除前导和尾随空格
		string s=word.concat("小鱼儿！");  //将指定的字符串连接到该字符串的末尾。
		int index1=s.indexof(',');
		int index2=s.indexof("!");
		//返回一个字符串，该字符串是此字符串的子字符串。 子字符串以指定索引处的字符开头，并扩展到该字符串的末尾。 
		system.out.println(s.substring(0, s.length()));
	}
}

练习37

package august12th;

public class subject6 {

	public static void main(string[] args) {
		system.out.println("***原歌词格式***");
		system.out.println("长亭外 古道边 芳草碧连天 晚风拂柳笛声残 夕阳山外山

");
		
		system.out.println("***拆分后词模式***");
		string s="长亭外 古道边 芳草碧连天 晚风拂柳笛声残 夕阳山外山";
		/*此方法返回的数组包含此字符串的每个子字符串，该字符串由与给定表达式匹配的另一个子字符串终止，
		 *或由字符串结尾终止。 数组中的子字符串按照它们在此字符串中的顺序排列。 
		 * 如果表达式与输入的任何部分不匹配，则生成的数组只有一个元素，即这个字符串。  */
		string[]arr=s.split(" ", 5);
		for(string i:arr){
			system.out.println(i);
		}
	}
}

练习38

package august12th;

import java.util.scanner;

public class subject7 {

	public static void main(string[] args) {
		scanner input=new scanner(system.in);
		system.out.println("请输入一串数字");
		string num=input.next();
		/*由start和end的参数s的顺序按顺序插入到指定目的地偏移量的该序列中，向上移动原始位于该位置的任何字符。
		 *  该序列的长度增加了end - start 。*/
		stringbuffer s=new stringbuffer(num);
		for(int i=s.length()-3;i>0;i=i-3){
			s.insert(i, ',');
		}
		system.out.println(s);
	}
}

ps:开始学java高级语法了，渐渐的感觉有些吃力，不过还好，9月1估计能开线下课了，加油吧，这次作业全用循环写了，有时候逻辑做了效果出不来找半天，不过解决了以后会有很大的成功感！

end

august15th.2020 homework

一周没更新了，今天补下作业。

练习39

定义一个方法 参数是字符串 返回int
要求 参数是生日 类型为 1900-1-1 返回 年龄

package august15th;
/**
 * 输入字符串生日，获取当前年龄
 * */
import java.text.simpledateformat;
import java.util.date;
import java.util.scanner;

public class subject {

	public static void main(string[] args) throws exception {
		scanner input=new scanner(system.in);
		system.out.println("请输入你的生日：(格式xxxx-x-x)");
		string s=input.next();
		simpledateformat f=new simpledateformat("yyyy-mm-dd");
		date d=f.parse(s);
		long date=d.gettime();
		date time=new date();
		long date1=time.gettime();
		system.out.println((date1-date)/1000/60/60/24/365);
		
	}
}

练习40

定义一个方法 参数是1 double 2 int 返回double
要求 参数1 是double 2是整数要求保留的小数点后几位 ，方法中对参数1进行格式化，在转换成double类型返回结果

package august15th;

import java.text.decimalformat;
import java.util.scanner;

public class subject2 {

	public static void main(string[] args) {
		double dec;
		scanner input = new scanner(system.in);
		system.out.println("请输入一个保留小数点后5位的数");
		double n = input.nextdouble();
		system.out.println("请输入想要保留小数点后几位?(可选1、2、3、4)");
		int n1 = input.nextint();
		switch(n1){
		case 1:
	
			system.out.println(new decimalformat("#.#").format(n));
			break;
		case 2:
			system.out.println(new decimalformat("#.##").format(n));
			break;
		case 3:
			system.out.println(new decimalformat("#.###").format(n));
			break;
		case 4:
			system.out.println(new decimalformat("#.####").format(n));
		}
	}

}

练习41

定义一个方法 参数是file类对象 ，返回字符串
要求 参数的一个文件，方法中 得到 文件的最后一次修改日期，格式化格式为 2020-1-1 11:20:33 把格式化后的字符串 返回

package august15th;

import java.io.file;
import java.io.ioexception;
import java.text.format;
import java.text.simpledateformat;
import java.util.calendar;
import java.util.date;


public class subject3 {

	public static void main(string[] args) throws ioexception {
		file f=new file("d://a.txt");
		long time=f.lastmodified();
		date d=new date(time);
		format simpledateformat=new simpledateformat("yyyy-mm-dd hh:mm:ss");
		
		calendar cal=calendar.getinstance();
		cal.settimeinmillis(f.lastmodified());
		string time1=simpledateformat.format(cal.gettime());
		system.out.println(time1);
	}
	
}

这道题不是很懂，网上找了下类似的参考一下！

练习42

定义一个方法 参数是file类对象 ，返回字符串
要求 参数的一个文件，方法中 得到 文件的大小，要求返回文件的大小 可以自动转换为 byte kb mb gb 返回字符串

package august15th;

import java.io.file;

public class subject4 {

	public static void main(string[] args) {
		file f=new file("d:/a/a.txt/w.txt");
		long a=f.length();
		system.out.println(a);
		system.out.println((f.length()/1024.0/1024.0));
	}
	
}

ps:感觉作页越来越难了，有什么不对的欢迎大家指出来！！
end

august18th.2020 homework

练习43

封装一个方法可以复制文件
返回类型 boolean 复制是否成功
参数源文件，目标目录（这题做的有点问题！！）

package august18th;

import java.io.file;
import java.io.fileinputstream;
import java.io.fileoutputstream;
import java.io.ioexception;

public class subject {

	public static void main(string[] args) {
		file f=null;
		file o=null;
		fileoutputstream out=null;
		fileinputstream in=null;
		try{
			f=new file("e:/java76/java/io/test/a.txt");
			o=new file("e:/java76/java/io/java/b.txt");
			in=new fileinputstream(f);
			out=new fileoutputstream(o);
			byte[]b=new byte[1024];
			for(int count=0;(count=in.read(b))!=-1;){
				out.write(b,0,count);
				out.flush();
			}
			system.out.println("复制成功");
		}catch(exception e){
			e.printstacktrace();
			system.out.println("复制失败");
		}finally{
			try{
				in.close();
			}catch(ioexception e){
				e.printstacktrace();
			}
		}	try{
			out.close();
		}catch(ioexception e){
			e.printstacktrace();
		}
	}
}

练习44

封装一个方法 可以把指定的内容输出到指定的目录文件
返回类型 boolean
参数（内容，目标文件）

package august18th;

import java.io.file;
import java.io.fileinputstream;
import java.io.fileoutputstream;
import java.io.ioexception;
import java.io.inputstream;
import java.io.outputstream;

public class subject2 {

	public static void main(string[] args) throws exception {
		file f=new file("e:"+file.separator+"java76/a.txt");       //目标文件输入流
		inputstream is=new fileinputstream(f);
		byte[]c=new byte[1024];
		//string s=" asdf";
//		for(int count=0;(count=is.read(c))!=-1;){
//			s+=new string(c,0,count);
//		}
//		system.out.println(s);
		
		is.close();
		
		file f1=new file("e:"+file.separator+"java76/a.txt");      //目标文件输出流
		outputstream out=new fileoutputstream(f1,true);
		string t="你好";
		out.write(t.getbytes());
		out.write(t.getbytes());
		out.close();
		
	}

}

练习45

封装一个方法 读取一个文本文件
返回类型 sting 读取的文件内容
参数（源文件）

package august18th;

import java.io.file;
import java.io.filenotfoundexception;
import java.io.filereader;
import java.io.filewriter;
import java.io.reader;
import java.io.writer;

public class subject3 {

	public static void main(string[] args) throws exception {     //字符输入输出流读写！
		file f=new file("d:"+file.separator+"a.txt");
		reader read=new filereader(f);
		char[]c=new char[3];
		string s=" ";
		for(int count=0;(count=read.read(c))!=-1;){
			s+=new string(c,0,count);
		}
		system.out.println(s);
		
		file f1=new file("d:"+file.separator+"a.txt");
		writer w=new filewriter(f1);
		w.write("大保健");
		w.flush();
		w.close();
	}
	
}

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end

august19th.2020 homework

练习46

使用 bufferedreader 读取一个.txt 文件的内容

package august19th;

import java.io.bufferedreader;
import java.io.file;
import java.io.filereader;
import java.io.reader;


public class subject {


	public static void main(string[] args) throws exception {
		file f=new file("a.txt");
		//字符输入流
		reader r=new filereader(f);
		bufferedreader br=new bufferedreader(r,1024*1024);
//		string s=br.readline();
//		system.out.println(s);
//		string s1=br.readline();
//		system.out.println(s1);
		string s=" ";
		for(string sline=" ";(sline=br.readline())!=null;){
			 s+= sline+"
";
		}
		system.out.println(s);
		r.close();
		br.close();
	}
}

练习47

objectinputstream， objectoutputstream ，实现对象的序列号和反序列化习47

package august19th;

import java.io.file;
import java.io.fileinputstream;
import java.io.fileoutputstream;
import java.io.inputstream;
import java.io.objectinputstream;
import java.io.objectoutputstream;
import java.io.outputstream;
import java.io.serializable;

public class subject3 {

	public static void main(string[] args) throws exception {
//		users u = new users(1, "333");
		file f = new file("a.txt");
//		序列话操作
//		outputstream w = new fileoutputstream(f);
//		objectoutputstream out = new objectoutputstream(w);

//		out.writeobject(u);
//		out.flush();
		
		//反序列化操作
		inputstream o=new fileinputstream(f);
		objectinputstream in=new objectinputstream(o);
		users u=(users)in.readobject();
		system.out.println(u.getage()+" "+u.getname());
	}

}

class users implements serializable {
	private int age;
	private string name;

	public int getage() {
		return age;
	}

	public void setage(int age) {
		this.age = age;
	}

	public string getname() {
		return name;
	}

	public void setname(string name) {
		this.name = name;
	}

	public users() {
		super();
	}

	public users(int age, string name) {
		super();
		this.age = age;
		this.name = name;
	}

}

练习48

使用继承和实现接口的两种方法，开启子线程复制 一个文件

package august19th;

import java.io.file;
import java.io.fileinputstream;
import java.io.fileoutputstream;
import java.io.ioexception;

public class subject2 extends thread {
	
	public void run() {
		file f=null;
		file o=null;
		fileoutputstream out=null;
		fileinputstream in=null;
		try{
			f=new file("e:/java76/java/io/test/a.txt");
			o=new file("e:/java76/java/io/java/b.txt");
			in=new fileinputstream(f);
			out=new fileoutputstream(o);
			byte[]b=new byte[1024];
			for(int count=0;(count=in.read(b))!=-1;){
				out.write(b,0,count);
				out.flush();
			}
			system.out.println("复制成功");
		}catch(exception e){
			e.printstacktrace();
			system.out.println("复制失败");
		}finally{
			try{
				in.close();
			}catch(ioexception e){
				e.printstacktrace();
			}
		}	try{
			out.close();
		}catch(ioexception e){
			e.printstacktrace();
		}
	}

	public static void main(string[] args) {
		thread test=new thread(new subject2());
		test.start();
	}
}

class sub implements runnable{

	@override
	public void run() {
		// todo auto-generated method stub
		file f=null;
		file o=null;
		fileoutputstream out=null;
		fileinputstream in=null;
		try{
			f=new file("e:/java76/java/io/test/a.txt");
			o=new file("e:/java76/java/io/java/b.txt");
			in=new fileinputstream(f);
			out=new fileoutputstream(o);
			byte[]b=new byte[1024];
			for(int count=0;(count=in.read(b))!=-1;){
				out.write(b,0,count);
				out.flush();
			}
			system.out.println("复制成功");
		}catch(exception e){
			e.printstacktrace();
			system.out.println("复制失败");
		}finally{
			try{
				in.close();
			}catch(ioexception e){
				e.printstacktrace();
			}
		}	try{
			out.close();
		}catch(ioexception e){
			e.printstacktrace();
		}
	}
	
}

此系列完结，后续我会更新进阶版的编程题，大家一起进步！