停车场迭代开发：TXT解析、字符串转整数及对象创建技术问询

Hey there! Let's break down how to tackle this multi-object parking lot project task step by step. I'll walk you through the class design, file parsing logic, and key implementation details to make this work smoothly.

1. First, Design the Class Structure #

We'll use an abstract parent class for shared vehicle properties, then create subclasses for Auto and Bicycle to handle type-specific logic (even if you don't have unique methods yet, this structure scales well for future updates).

// Abstract parent class for all vehicles
abstract class Vehicle {
    protected int speed;
    protected int passengerCapacity;
    protected String serialNumber;
    protected boolean isLocked;

    public Vehicle(int speed, int passengerCapacity, String serialNumber, boolean isLocked) {
        this.speed = speed;
        this.passengerCapacity = passengerCapacity;
        this.serialNumber = serialNumber;
        this.isLocked = isLocked;
    }

    // Optional: Add a toString method for easy debugging
    @Override
    public String toString() {
        return String.format("Type: %s | Speed: %d | Capacity: %d | Serial: %s | Locked: %b",
                this.getClass().getSimpleName(), speed, passengerCapacity, serialNumber, isLocked);
    }
}

// Car subclass
class Auto extends Vehicle {
    public Auto(int speed, int passengerCapacity, String serialNumber, boolean isLocked) {
        super(speed, passengerCapacity, serialNumber, isLocked);
    }

    // Add car-specific methods here later (e.g., turnOnAC())
}

// Bicycle subclass
class Bicycle extends Vehicle {
    public Bicycle(int speed, int passengerCapacity, String serialNumber, boolean isLocked) {
        super(speed, passengerCapacity, serialNumber, isLocked);
    }

    // Add bicycle-specific methods here later (e.g., foldBike())
}

2. Read the File & Parse Each Line #

Next, we'll read the .txt file line by line, split each line using % as the delimiter, convert string values to their proper types, and create the corresponding vehicle objects.

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

public class ParkingLotDataProcessor {
    public static void main(String[] args) {
        String filePath = "parking_vehicles.txt"; // Replace with your actual file path
        List<Vehicle> parkingVehicles = new ArrayList<>();

        // Use try-with-resources to auto-close the file reader
        try (BufferedReader reader = new BufferedReader(new FileReader(filePath))) {
            String line;
            while ((line = reader.readLine()) != null) {
                // Skip empty lines to avoid errors
                if (line.trim().isEmpty()) continue;

                // Split the line into individual properties
                String[] vehicleProps = line.split("%");

                // Validate the line format first
                if (vehicleProps.length != 5) {
                    System.err.println("Skipping invalid line: " + line);
                    continue;
                }

                try {
                    // Parse each property to its correct type
                    String vehicleType = vehicleProps[0];
                    int speed = Integer.parseInt(vehicleProps[1]);
                    int capacity = Integer.parseInt(vehicleProps[2]);
                    String serialNum = vehicleProps[3];
                    boolean isLocked = Boolean.parseBoolean(vehicleProps[4]);

                    // Create the correct vehicle object based on type
                    Vehicle newVehicle;
                    switch (vehicleType) {
                        case "Auto":
                            newVehicle = new Auto(speed, capacity, serialNum, isLocked);
                            break;
                        case "Bicycle":
                            newVehicle = new Bicycle(speed, capacity, serialNum, isLocked);
                            break;
                        default:
                            System.err.println("Unknown vehicle type: " + vehicleType + " in line: " + line);
                            continue;
                    }

                    parkingVehicles.add(newVehicle);
                    System.out.println("Successfully created: " + newVehicle);

                } catch (NumberFormatException e) {
                    // Catch errors when converting strings to integers
                    System.err.println("Failed to parse numeric value in line: " + line + " | Error: " + e.getMessage());
                }
            }

            System.out.println("\nTotal vehicles processed: " + parkingVehicles.size());

        } catch (IOException e) {
            // Handle file reading errors (e.g., file not found)
            System.err.println("Error reading file: " + e.getMessage());
        }
    }
}

3. Key Implementation Notes #

• String to Integer Conversion: Use Integer.parseInt() for numeric fields, but always wrap this in a try-catch block to handle invalid number formats (like non-numeric characters in the speed/capacity fields).
• Boolean Parsing: Boolean.parseBoolean() will correctly convert "true" to true and "false" to false (note: it's case-sensitive in Java—only lowercase "true" will return true).
• File Safety: The try-with-resources syntax ensures the file reader is automatically closed, preventing resource leaks.
• Format Validation: Checking that each split line has exactly 5 parts avoids ArrayIndexOutOfBoundsException errors.

4. Future Expansion Tips #

• If you add more vehicle types later (e.g., Motorcycle), use a Factory Pattern to replace the switch statement for cleaner, more maintainable code.
• Extract the line-parsing logic into a separate method (like parseVehicleLine(String line)) to keep your main code organized.
• Store the parsed vehicle objects in a database or write them to a new file to integrate with future parking lot features (like check-in/check-out).

内容的提问来源于stack exchange，提问作者Steam261