Java实现联系人按姓名和手机号排序并输出文件求助

Hey there! Let's fix your sorting issue and get your contact list sorted properly. First, let's break down the gaps in your current code:

• Your CountLines method consumes the Scanner stream, so you can't read the actual contact data afterward
• You haven't added logic to parse each line into name-number pairs
• Missing comparator logic to sort contacts by name or phone number

Here's the revised, complete code that addresses all these points:

import java.io.File;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import java.util.Scanner;

public class ContactSorter {

    // Updated save method to preserve the original "Name - Number" format
    public static void Save(List<String[]> contacts, File f) throws Exception {
        // Use try-with-resources to auto-close the writer and avoid leaks
        try (PrintWriter output = new PrintWriter(f)) {
            for (String[] contact : contacts) {
                output.println(contact[0] + " - " + contact[1]);
            }
        }
    }

    // Read and parse contacts from file in one go (replaces your CountLines method)
    public static List<String[]> readContacts(File contactsFile) throws Exception {
        List<String[]> contacts = new ArrayList<>();
        try (Scanner reader = new Scanner(contactsFile)) {
            while (reader.hasNextLine()) {
                String line = reader.nextLine().trim();
                if (line.isEmpty()) {
                    continue; // Skip empty lines instead of stopping entirely
                }
                // Split each line using " - " as the delimiter to get name and number
                String[] parts = line.split(" - ");
                if (parts.length == 2) { // Ensure the line is in valid format
                    contacts.add(new String[]{parts[0].trim(), parts[1].trim()});
                }
            }
        }
        return contacts;
    }

    public static void main(String[] args) throws Exception {
        File contactsFile = new File("Contacts.txt");
        File sortedByNameFile = new File("SortedByName.txt");
        File sortedByNumberFile = new File("SortedByNumber.txt");

        // Step 1: Read all contacts from the input file
        List<String[]> contacts = readContacts(contactsFile);
        System.out.println("Total contacts found: " + contacts.size());

        // Step 2: Sort contacts by name (use String.CASE_INSENSITIVE_ORDER for case-agnostic sorting)
        List<String[]> sortedByName = new ArrayList<>(contacts);
        sortedByName.sort(Comparator.comparing(contact -> contact[0]));

        // Step 3: Sort contacts by phone number (string comparison works here since numbers are fixed-length)
        List<String[]> sortedByNumber = new ArrayList<>(contacts);
        sortedByNumber.sort(Comparator.comparing(contact -> contact[1]));

        // Step 4: Save sorted lists to their respective files
        Save(sortedByName, sortedByNameFile);
        Save(sortedByNumber, sortedByNumberFile);

        System.out.println("Sorting done! Check SortedByName.txt and SortedByNumber.txt for results.");
    }
}

Key improvements explained: #

• readContacts method: Replaces your CountLines method with a more robust approach that reads and parses contacts in one pass, using an ArrayList to avoid pre-defining array sizes (which is error-prone).
• Try-with-resources: Automatically closes Scanner and PrintWriter to prevent resource leaks, so you don't need manual close() calls.
• Clear sorting logic: Uses Java's Comparator.comparing() to create simple, readable sorters. For case-insensitive name sorting, replace Comparator.comparing(contact -> contact[0]) with Comparator.comparing(contact -> contact[0], String.CASE_INSENSITIVE_ORDER).
• Proper output formatting: The Save method now writes lines in the original "Name - Number" format instead of space-separated values.

Testing this with your sample data:

Original data:
Michael - 0001234567
Robert - 0019234568
Jacob - 0011234567

• Sorted by name: Jacob - 0011234567, Michael - 0001234567, Robert - 0019234568 (matches your expected result)
• Sorted by phone number: Michael - 0001234567, Jacob - 0011234567, Robert - 0019234568 (also matches your expected result)

内容的提问来源于stack exchange，提问作者MrOutside