Java 如何从文件读入对象（构造函数）

所以我得到了一个名为

Car

的类，在那里我存储了与汽车相关的信息。 看起来像这样

public class Car {
    private String reg;
    private String model;
    private int year;
    private String name;
    private String date;
    private int millage;
   private String service;

    //Constructor for the Car Class 
   public Car (String reg, String model,int year, String name, String date, int millage, String service){
       this.reg = reg;
       this.millage = millage;
       this.date = date;
       this.service = service;
       this.name = name;
       this.model = model;
       this.year = year;
}

用户输入有关汽车的信息后，所有信息都存储在一个数组列表中，数组列表中的数据被打印到一个.txt文件中存储

到目前为止文本文件的外观如何

Ford-ERI56Y-2003-Tuva Larsson-2020/24/01-Large Service    
Volvo -JDV810-1999-Åsa Eriksson-2020/24/01-Small Service

我希望能够扫描文本文件，并将文件内容添加回

ArrayList

，以便以后使用

到目前为止我有这个代码

 BufferedReader br = new BufferedReader(new FileReader(file));
       String read;
         while ((read = br.readLine()) != null) {
                    String [] carParts = read.split("-");

carList.add(read)


         }


}

这不起作用，因为

ArrayList

使用

Car

而不是

String

ArrayList<Car> carList = new ArrayList<>();

ArrayList carList=new ArrayList（）；

对您的

汽车

类进行了一些更改，因此现在看起来如下所示：

import java.time.LocalDate;

public class Car {

    private final String registration;
    public String getRegistration() { return registration; }

    private final String model;
    public String getModel() { return model; }

    private final Integer year;
    public Integer getYear() { return year; }

    private final String name;
    public String getName() { return name; }

    private final LocalDate date;
    public LocalDate getDate() { return date; }

    private final Integer mileage;
    public Integer getMileage() { return mileage; }

    private final String service;
    public String getService() { return service; }

    public Car(String registration, String model, Integer year, String name, LocalDate date, Integer mileage,
    String service) {
    this.registration = registration;
    this.model = model;
    this.year = year;
    this.name = name;
    this.date = date;
    this.mileage = mileage;
    this.service = service;
    }

    @Override
    public String toString() {
    return "Car{" +
        "registration='" + registration + '\'' +
        ", model='" + model + '\'' +
        ", year=" + year +
        ", name='" + name + '\'' +
        ", date=" + date +
        ", mileage=" + mileage +
        ", service='" + service + '\'' +
        '}';
    }

}

另外，包含条目的example.txt文件缺少几列，因此我继续添加这些内容：

ERI56Y-Ford-2003-Tuva Larsson-2020/24/01-60000-Large Service
JDV810-Volvo-1999-Åsa Eriksson-2020/24/01-750000-Small Service`

现在pojo和文本文件都已确定，从中读取并创建汽车列表非常容易。检查以下示例：

private static List<Car> readFromFile(String filePath) {
    try (Stream<String> lines = Files.lines(Paths.get(filePath))) {
        return lines
        .map(line -> line.split("-"))
        .map(parts -> new Car(parts[0], parts[1],
            Integer.valueOf(parts[2]), parts[3],
            LocalDate.parse(parts[4], DateTimeFormatter.ofPattern("yyyy/dd/MM")),
            Integer.valueOf(parts[5]), parts[6]))
        .collect(Collectors.toList());
    } catch (IOException e) {
        e.printStackTrace();
    }
    return Collections.emptyList();
}

---

您需要通过调用其构造函数并传递carParts数组中所需的参数来创建一个Car。然后您需要将该车添加到列表中：

car car=new car（carParts[0]，…）；添加（汽车）。
public static void main(String... args) {
    readFromFile(System.getProperty("user.home") + "/cars.txt").forEach(System.out::println);
    }