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

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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

在这里插入图片描述

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

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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

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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

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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

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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

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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

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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

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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

在这里插入图片描述

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

在这里插入图片描述

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

在这里插入图片描述

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

在这里插入图片描述

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

在这里插入图片描述

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

在这里插入图片描述

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

在这里插入图片描述

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
在这里插入图片描述

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

在这里插入图片描述

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

在这里插入图片描述

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

在这里插入图片描述

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

在这里插入图片描述

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

在这里插入图片描述

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

在这里插入图片描述

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

在这里插入图片描述

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

在这里插入图片描述

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

在这里插入图片描述

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();
    }
    
}

PS:今天是我27岁生日，没有惊喜，没有意外，只有老爸晚上给我发了个生日红包，果然还是只有家人最关心自己，加油吧，定了场livehouse的票，第一次去看，真的很喜欢Hip-hop，加油吧，心态放端正就好！！
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！

标签： java 开发语言算法

本文转载自: https://blog.csdn.net/m0_67393593/article/details/126737963
版权归原作者 m0_67393593 所有，如有侵权，请联系我们删除。

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

练习2

练习3

练习4

练习5

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

练习7

练习8

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

练习10

人机猜拳（石头剪刀布）

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。

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。

任意两个整数之间的随机数：

练习13

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

练习14

ATM系统,登录，显示余额、存钱、取钱、退出功能。

练习15

自定义数组 ，参数 1 数组 2 字符串 返回数组 int

July27th.2020 homework

练习16

练习17

July28th.2020 homework

练习18

练习19

练习20

July31th.2020 homework

练习21

练习22

Auguest3rd.2020 homework

练习23

练习24

August4th.2020 homework

练习25

练习26

练习27

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。

August11th.2020 homework

练习29

练习30

练习31

August12th.2020 homework

练习32

练习33

练习34

练习35

练习36

练习37

练习38

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！

August15th.2020 homework

一周没更新了，今天补下作业。

练习39

练习40

练习41

练习42

August18th.2020 homework

练习43

练习44

练习45

August19th.2020 homework

练习46

练习47

练习48

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。

自定义方法：两个 int参数，返回随机数int。

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

自定义数组，参数 1 数组 2 字符串返回数组 int

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。