Java 入门20 ArrayList 小案例实践

案例一 删除 成绩中不满住80分的成绩

package com.heima.StringDemo;

import java.util.ArrayList;

public class ArrayList3 {
    public static void main(String[] args) {
        //创建ArrayList 对象  并使用泛型指定整数
        ArrayList<Integer> list = new ArrayList();

        //添加同学的成绩
        list.add(98);
        list.add(77);
        list.add(66);
        list.add(89);
        list.add(79);
        list.add(50);
        list.add(100);

        //循环ArrayList
        for (int i = 0; i < list.size(); i++) {
            System.out.println(list.get(i));
            //判断成绩是否低于80  低于80 则删除
            if (list.get(i) <=80) {
                list.remove(i);
                //从前面往后面删除  删除元素值后,后面的元素值要向前挪 所以i--;
                i--;
            }
        }

        //打印删除后的学生成绩
        System.out.println(list);
    }
}

案例二 影片信息在程序中的存储

Movie 类

package com.heima.StringDemo;

public class Movie {
    private String name;
    private double scores;
    private String filmPerson;

    //创造无参构造器

    public Movie() {
    }

    //创造有参构造器
    public Movie(String name, double scores, String filmPerson) {
        this.name = name;
        this.scores = scores;
        this.filmPerson = filmPerson;
    }

    //set get方法创建

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public double getScores() {
        return scores;
    }

    public void setScores(double scores) {
        this.scores = scores;
    }

    public String getFilmPerson() {
        return filmPerson;
    }

    public void setFilmPerson(String filmPerson) {
        this.filmPerson = filmPerson;
    }
}

Test 测试类

package com.heima.StringDemo;

import java.util.ArrayList;
import java.util.Scanner;

/*
电影Test类
需求:定义电影类(名称,分值,演员),创建3个电影对象,代表散步影片,存入集合中并遍历
*/
public class Test {
    public static void main(String[] args) {
        //创造一个ArrayList 集合用来存储movies
        ArrayList<Movie> list = new ArrayList();
        Movie a = new Movie("肖申克的救赎", 9.7, "罗伯特");
        Movie b = new Movie("霸王别姬", 9.1, "虞姬");
        Movie c = new Movie("阿甘正传", 10.0, "阿甘");

        list.add(a);
        list.add(b);
        list.add(c);

        for (int i = 0; i < list.size(); i++) {
            Movie child=list.get(i);
            System.out.println(child.getName()+"评分"+child.getScores()+"主演"+child.getFilmPerson());
        }
    }
}

 案例三 元素搜索

 Student类

package com.heima.StringDemo;

public class Student {
    private String name;
    private int studentNum;
    private int age;
    private String studentClass;

    //创建有参构造器

    public Student(String name, int studentNum, int age, String studentClass) {
        this.name = name;
        this.studentNum = studentNum;
        this.age = age;
        this.studentClass = studentClass;
    }


    //创建无参构造器

    public Student() {
    }

    //get set 创建

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public double getStudentNum() {
        return studentNum;
    }

    public void setStudentNum(int studentNum) {
        this.studentNum = studentNum;
    }

    public int getAge() {
        return age;
    }

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

    public String getStudentClass() {
        return studentClass;
    }

    public void setStudentClass(String studentClass) {
        this.studentClass = studentClass;
    }
}

Test1 测试类

package com.heima.StringDemo;

import java.util.ArrayList;
import java.util.Scanner;

public class Test1 {
    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        //创建ArrayList 存储Student产生的对象
        ArrayList<Student> studentList = new ArrayList<>();

        //创建学生
        Student Stu = new Student("叶孤城", 20189812, 18, "二年级一班");
        Student Stu1 = new Student("东方不败", 20189813, 18, "二年级一班");
        Student Stu2 = new Student("西门吹雪", 20189814, 18, "二年级一班");
        Student Stu3 = new Student("梅超风", 20189815, 18, "二年级一班");

        //添加进StudentList
        studentList.add(Stu);
        studentList.add(Stu1);
        studentList.add(Stu2);
        studentList.add(Stu3);

        //循环展示studentList集合中的元素信息
        for (int i = 0; i < studentList.size(); i++) {
            Student child = studentList.get(i);
            System.out.println(child.getName() + "\t年纪 \t" + child.getAge() + "学号\t" + child.getStudentNum() + "年级\t" + child.getStudentClass());
        }
        while (true) {
            System.out.println("请输入学号");
            int num = sc.nextInt();
            Student s = getSearchMsg(studentList, num);
            if(s!=null){
                System.out.println(s.getName() + "\t年纪 \t" + s.getAge() + "学号\t" + s.getStudentNum() + "年级\t" + s.getStudentClass());
                System.out.println("查询完毕");
            }else{
                System.out.println("查无此人");
            }
            //查询结束
        }
    }

    public static Student getSearchMsg(ArrayList<Student> a, int num) {
        for (int i = 0; i < a.size(); i++) {
            Student child = a.get(i);
            //相同 则匹配上
            if (child.getStudentNum() == num) {
                return child;
            }
        }
        return null;//查无此学号
    }

}

 案例四

Account类

   public Account() {
   }

   //创建有参构造器
   public Account(String user, int pass, double money, double basic) {
      this.user = user;
      this.pass = pass;
      this.money = money;
      this.basic = basic;
   }

   //get set方法

   public String getUser() {
      return user;
   }

   public void setUser(String user) {
      this.user = user;
   }

   public int getPass() {
      return pass;
   }

   public void setPass(int pass) {
      this.pass = pass;
   }

   public double getMoney() {
      return money;
   }

   public void setMoney(double money) {
      this.money = money;
   }

   public double getBasic() {
      return basic;
   }

   public void setBasic(double basic) {
      this.basic = basic;
   }

   public int getAccounts() {
      return accounts;
   }

   public void setAccounts(int accounts) {
      this.accounts = accounts;
   }
}

Test 类

package com.heima.ATM;

import java.util.ArrayList;
import java.util.Random;
import java.util.Scanner;

public class Test {
    public static void main(String[] args) {
        //创建ArrayList 用来存储 Account实例对象
        ArrayList<Account> accountList = new ArrayList<>();

        while (true) {
            firstPage(accountList);
        }
    }

    //首页方法
    public static void firstPage(ArrayList<Account> accountList) {
        Scanner sc = new Scanner(System.in);
        while (true) {
            System.out.println("欢迎登录ATM银行系统");
            System.out.println("请输入你需要选择的内容");
            System.out.println("----------------");
            System.out.println("1 登录");
            System.out.println("2 注册");
            int command = sc.nextInt();
            switch (command) {
                case 1:
                    Account child = login(accountList);
                    if (child == null) {
                        System.out.println("不存在该账号");
                    } else {
                        loginSuccess(accountList, child);
                    }
                    break;
                case 2:
                    register(accountList);
                    break;
                default:
                    System.out.println("输入指令错误");
            }
        }
    }

    //登录成功后方法
    public static void loginSuccess(ArrayList<Account> accountList, Account child) {
        Scanner sc = new Scanner(System.in);
        //获取用户名 信息
        //登录成功后 显示用户名 及要操作的内容
        while (true) {
            System.out.println("=========欢迎进入到操作界面============");
            System.out.println("1查询");
            System.out.println("2存款");
            System.out.println("3取款");
            System.out.println("4转账");
            System.out.println("5修改密码");
            System.out.println("6退出");
            System.out.println("7注销账户");
            System.out.println("请输入当前操作指令");
            int command = sc.nextInt();
            switch (command) {
                //查询
                case 1:
                    System.out.println("您的存款有: \t" + child.getMoney());
                    break;
                //存款
                case 2:
                    saveMoney(child);
                    break;
                //取款
                case 3:
                    takeMoney(child);
                    break;
                case 4:
                    giveMoney(accountList, child);
                    break;
                case 5:
                    changePass(child);
                    break;
                case 6:
                    firstPage(accountList);
                    return;
                case 7:
                    deleteUser(accountList, child);
                    break;
                default:
                    System.out.println("指令输入错误");
            }
        }
    }

    //登录
    public static Account login(ArrayList<Account> accountList) {
        Scanner sc = new Scanner(System.in);
        while (true) {
            boolean flag = false;
            System.out.println("请输入用户名:user");
            String user = sc.next();
            System.out.println("请输入密码:pass");
            int pass = sc.nextInt();
            //锁 用来判断是否存在该账号 默认不存在
            for (int i = 0; i < accountList.size(); i++) {
                Account child = accountList.get(i);
                if (child.getUser().equals(user)) {
                    //存在 改变锁的状态
                    flag = true;
                    //判断pass 是否存在
                    if (child.getPass() == pass) {
                        //登录成功
                        System.out.println("登录成功");
                        return child;
                    } else {
                        System.out.println("密码输入错误,请重新输入");
                        break;
                    }
                }
            }
            if (!flag) {
                return null;
            }
        }
    }

    //注册
    public static void register(ArrayList<Account> accountList) {
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入用户名:user");
        String user = sc.next();
        System.out.println("请输入密码:pass");
        int pass = sc.nextInt();
        //创建Account实例
        Account account = new Account(user, pass, 0, 5000);
        //向accountList中添加账户
        accountList.add(account);
        //随机生成6为位数的账户
        Random r = new Random();
        boolean flag = false;
        int accounts = 0;
        while (true) {
            accounts = r.nextInt(99999) + 900000;
            //默认不存在该账户
            flag = false;
            for (int j = 0; j < accountList.size(); j++) {
                if (accountList.get(j).getAccounts() == accounts) {
                    //改变锁
                    flag = true;
                }
            }
            //账户中不存在该账户
            if (!flag) {
                account.setAccounts(accounts);
                System.out.println("注册成功" + "您的卡号是" + accounts);
                break;
            }
        }
    }

    //存款
    public static void saveMoney(Account child) {
        Scanner sc = new Scanner(System.in);
        while (true) {
            System.out.println("请输入您要存的金额");
            //输入你要存的数目
            double money = sc.nextInt();
            if (money < 0) {
                System.out.println("输入金额错误");
            } else {
                //存款
                double oldMoney = child.getMoney();
                double newMoney = money + oldMoney;
                //修改金钱数目
                child.setMoney(newMoney);
                System.out.println("你存款成功" + "现在金额为" + child.getMoney());
                break;
            }
        }
    }

    //取款
    public static void takeMoney(Account child) {
        //获取输入流对象
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入要取款的金额");
        double money = sc.nextDouble();
        double oldMoney = child.getMoney();
        if (money > oldMoney) {
            System.out.println("余额不足");
        } else {
            System.out.println("你取出了" + money + "余额还有" + (oldMoney - money));
            double newMoney = oldMoney - money;
            child.setMoney(newMoney);
            System.out.println("取款成功");
        }
    }

    //转账
    public static void giveMoney(ArrayList<Account> accountArrayList, Account child) {
        Scanner sc = new Scanner(System.in);
        //用户只有一个
        if (accountArrayList.size() <= 1) {
            System.out.println("ATM系统中只有你 一个用户 ,请注册新账户");
        }
        //存在多个用户
        if (accountArrayList.size() > 1) {
            System.out.println("请输入要转账的账户卡号");
            //获取要转账的号码
            boolean result = false;
            Account newAccounts=null;
            while (true) {
                int accounts = sc.nextInt();
                //卡号范围正确与否
                if (accounts > 99999 && accounts < 1000000) {
                    //定义锁
                    for (int i = 0; i < accountArrayList.size(); i++) {
                        //存在账户
                        if (accountArrayList.get(i).getAccounts() == accounts && accountArrayList.get(i).getAccounts()!= child.getAccounts()) {
                                    newAccounts=accountArrayList.get(i);
                                    result = true;
                                    break;
                        }
                    }
                    //存在账户
                    if(result){
                       //开始转账 旧账户 扣钱  新账户加钱
                        System.out.println("请输入要转账的金额");
                        double money=sc.nextDouble();
                        //金额合适
                        if(money>=0 && money<=child.getMoney()){
                            //扣钱
                            child.setMoney(child.getMoney()-money);
                            System.out.println(child.getMoney()+"现在有多少钱");
                            //加钱
                            newAccounts.setMoney(newAccounts.getMoney()+money);
                            System.out.println(newAccounts.getMoney()+"现在有多少钱");
                            System.out.println(newAccounts.getUser()+"钱2"+newAccounts.getMoney());
                            //转账完成
                            System.out.println("转账完成");
                            //跳出循环
                            loginSuccess(accountArrayList,child);
                            break;
                        }else{
                            System.out.println("金额错误 或者 你也没钱 转什么");
                        }
                    }
                } else {
                    System.out.println("您输入的账户长度有误,6位长度");
                }
            }
        }
    }


    //修改密码
    public static void changePass(Account child) {
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入新的密码");
        int newPass = sc.nextInt();
        child.setPass(newPass);
        //修改成功
        System.out.println("密码修改成功");
    }

    //注销账户
    public static void deleteUser(ArrayList<Account> accountArrayList, Account child) {
        //判断账户内是否有钱
        if (child.getMoney() == 0) {
            //可以注销
            for (int i = 0; i < accountArrayList.size(); i++) {
                Account kid = accountArrayList.get(i);
                if (kid.getUser().equals(child.getUser())) {
                    //删除
                    System.out.println(accountArrayList.remove(i) + "删除成功");
                    firstPage(accountArrayList);
                    //退出循环
                    break;
                }
            }
        } else {
            System.out.println("你的账户还有钱" + child.getMoney() + "取完才可以注销");
        }
    }
}