2、利用文件构建用户电话号码本。（需实现增、删、查（按指定属性排序并查询）、改、显示的功能）。Java

可以使用Java中的文件操作API来实现用户电话号码本的增、删、查、改和显示功能，以下是一个简单的实现：

import java.io.*;
import java.util.*;

public class PhoneNumberBook {
    private static final String FILENAME = "phonebook.txt"; // 文件名

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int choice = 0;
        do {
            System.out.println("请选择操作：");
            System.out.println("1. 添加联系人");
            System.out.println("2. 删除联系人");
            System.out.println("3. 查询联系人");
            System.out.println("4. 修改联系人");
            System.out.println("5. 显示联系人");
            System.out.println("0. 退出");
            System.out.print("请输入选项：");
            choice = scanner.nextInt();
            switch (choice) {
                case 1:
                    addContact();
                    break;
                case 2:
                    deleteContact();
                    break;
                case 3:
                    searchContact();
                    break;
                case 4:
                    modifyContact();
                    break;
                case 5:
                    displayContacts();
                    break;
                case 0:
                    System.out.println("谢谢使用！");
                    break;
                default:
                    System.out.println("无效选项，请重新输入！");
                    break;
            }
        } while (choice != 0);
    }

    // 添加联系人
    private static void addContact() {
        Scanner scanner = new Scanner(System.in);
        System.out.print("请输入姓名：");
        String name = scanner.nextLine();
        System.out.print("请输入电话号码：");
        String phone = scanner.nextLine();
        Contact contact = new Contact(name, phone);
        try (BufferedWriter writer = new BufferedWriter(new FileWriter(FILENAME, true))) {
            writer.write(contact.toString());
            writer.newLine();
            System.out.println("添加联系人成功！");
        } catch (IOException e) {
            System.out.println("添加联系人失败：" + e.getMessage());
        }
    }

    // 删除联系人
    private static void deleteContact() {
        Scanner scanner = new Scanner(System.in);
        System.out.print("请输入要删除的联系人姓名：");
        String name = scanner.nextLine();
        List<Contact> contacts = readContacts();
        boolean found = false;
        try (BufferedWriter writer = new BufferedWriter(new FileWriter(FILENAME))) {
            for (Contact contact : contacts) {
                if (contact.getName().equals(name)) {
                    found = true;
                } else {
                    writer.write(contact.toString());
                    writer.newLine();
                }
            }
            if (found) {
                System.out.println("删除联系人成功！");
            } else {
                System.out.println("未找到该联系人！");
            }
        } catch (IOException e) {
            System.out.println("删除联系人失败：" + e.getMessage());
        }
    }

    // 查询联系人
    private static void searchContact() {
        Scanner scanner = new Scanner(System.in);
        System.out.print("请输入要查询的联系人姓名：");
        String name = scanner.nextLine();
        List<Contact> contacts = readContacts();
        List<Contact> results = new ArrayList<>();
        for (Contact contact : contacts) {
            if (contact.getName().contains(name)) {
                results.add(contact);
            }
        }
        if (results.isEmpty()) {
            System.out.println("未找到匹配的联系人！");
        } else {
            System.out.println("查询结果如下：");
            sortByProperty(results);
            displayContacts(results);
        }
    }

    // 修改联系人
    private static void modifyContact() {
        Scanner scanner = new Scanner(System.in);
        System.out.print("请输入要修改的联系人姓名：");
        String name = scanner.nextLine();
        List<Contact> contacts = readContacts();
        boolean found = false;
        try (BufferedWriter writer = new BufferedWriter(new FileWriter(FILENAME))) {
            for (Contact contact : contacts) {
                if (contact.getName().equals(name)) {
                    System.out.print("请输入新的电话号码：");
                    String phone = scanner.nextLine();
                    contact.setPhone(phone);
                    writer.write(contact.toString());
                    writer.newLine();
                    found = true;
                } else {
                    writer.write(contact.toString());
                    writer.newLine();
                }
            }
            if (found) {
                System.out.println("修改联系人成功！");
            } else {
                System.out.println("未找到该联系人！");
            }
        } catch (IOException e) {
            System.out.println("修改联系人失败：" + e.getMessage());
        }
    }

    // 显示联系人
    private static void displayContacts() {
        List<Contact> contacts = readContacts();
        if (contacts.isEmpty()) {
            System.out.println("电话号码本为空！");
        } else {
            sortByProperty(contacts);
            displayContacts(contacts);
        }
    }

    // 读取联系人信息
    private static List<Contact> readContacts() {
        List<Contact> contacts = new ArrayList<>();
        try (BufferedReader reader = new BufferedReader(new FileReader(FILENAME))) {
            String line = null;
            while ((line = reader.readLine()) != null) {
                Contact contact = Contact.fromString(line);
                if (contact != null) {
                    contacts.add(contact);
                }
            }
        } catch (IOException e) {
            System.out.println("读取文件失败：" + e.getMessage());
        }
        return contacts;
    }

    // 按指定属性排序并显示联系人
    private static void sortByProperty(List<Contact> contacts) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请选择排序属性：");
        System.out.println("1. 姓名");
        System.out.println("2. 电话号码");
        System.out.print("请输入选项：");
        int choice = scanner.nextInt();
        Comparator<Contact> comparator = null;
        switch (choice) {
            case 1:
                comparator = Comparator.comparing(Contact::getName);
                break;
            case 2:
                comparator = Comparator.comparing(Contact::getPhone);
                break;
            default:
                System.out.println("无效选项，使用默认排序规则：按姓名排序。");
                comparator = Comparator.comparing(Contact::getName);
                break;
        }
        contacts.sort(comparator);
    }

    // 显示联系人
    private static void displayContacts(List<Contact> contacts) {
        System.out.println("姓名\t\t电话号码");
        for (Contact contact : contacts) {
            System.out.println(contact.getName() + "\t\t" + contact.getPhone());
        }
    }

    // 联系人类
    private static class Contact {
        private String name;
        private String phone;

        public Contact(String name, String phone) {
            this.name = name;
            this.phone = phone;
        }

        public String getName() {
            return name;
        }

        public String getPhone() {
            return phone;
        }

        public void setPhone(String phone) {
            this.phone = phone;
        }

        @Override
        public String toString() {
            return name + "," + phone;
        }

        public static Contact fromString(String str) {
            String[] parts = str.split(",");
            if (parts.length == 2) {
                return new Contact(parts[0], parts[1]);
            } else {
                return null;
            }
        }
    }
}

在程序中，我们使用了一个`Contact`类来表示每个联系人，其中包含姓名和电话号码两个属性。程序启动后，用户可以选择添加、删除、查询、修改和显示联系人信息。联系人信息保存在一个名为`phonebook.txt`的文本文件中，每行表示一个联系人，格式为`姓名,电话号码`。在实现查询和排序时，我们使用了Java集合框架中的`List`和`Comparator`来方便地对联系人进行排序和过滤。