如何修复'；NotSerializableException:java.time.format.DateTimeFormatter'；错误

我正在尝试使用ObjectOutputStream将Arraylist中的所有对象保存到文件。对象的一个属性是LocalDate，每当我尝试写入文件时，都会返回一个错误NotSerializableException:java.time.format.DateTimeFormatter，尽管没有任何LocalDate的DateTimeFormatter

完全错误：

java.io.NotSerializableException: java.time.format.DateTimeFormatter
    at java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1185)
    at java.base/java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1553)
    at java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1510)
    at java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
    at java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
    at java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:349)
    at java.base/java.util.ArrayList.writeObject(ArrayList.java:791)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:564)
    at java.base/java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1130)
    at java.base/java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1497)
    at java.base/java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1433)
    at java.base/java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1179)
    at java.base/java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:349)
    at BikeNow.saveRent(BikeNow.java:330)
    at BikeNow.main(BikeNow.java:114)

使用对象输出流的方法

public void saveRent() {
        //Create file and object output stream
        try {
            FileOutputStream fos = new FileOutputStream("tmp.dat");
            ObjectOutputStream oos = new ObjectOutputStream(fos);

            //Write array to file
            oos.writeObject(rents);
            oos.close();
            fos.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

试图保存到文件的对象的示例

rents.add(new Rent(0001, "John Smith", true, "Roubaix Sport", LocalDate.of(2019, 03, 06), LocalDate.of(2019, 04, 05), 30, true));

对象类

import java.io.Serializable;
import java.time.LocalDate;

public class Rent extends Customer implements Serializable {
    private LocalDate startDate;
    private LocalDate endDate;
    private int duration;
    private boolean overdue;

public Rent(int customerID, String customerName,  boolean renting, String bikeRented, LocalDate startDate, LocalDate endDate, int duration, boolean overdue) {
        super(customerID, customerName,  renting, bikeRented);
        this.startDate = startDate;
        this.endDate = endDate;
        this.duration = duration;
        this.overdue = overdue;
    }

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这里没有太多的内容，但很明显，当您编写对象时，您正在尝试编写DateTimeFormatter。这让我相信Customer中定义了一个，但由于DTF没有实现Serializable，它就爆炸了

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最好的解决方案是编辑Customer类以正确序列化。另一种选择是将其填充到您的Rent类中，但如果字段是私有的，则这可能是不可能的。

在检查Customer类时，我意识到我有一个未使用的DateTimeFormatter，我无意中复制粘贴了它而没有意识到。去掉这个问题就解决了