java - 无法存储不可序列化对象的引用

Question

嗨，团队最近我开始使用 I/O 包，但遇到了一个问题，如下面的代码所示，我有一个类 Identity，其中包含非序列化类 Address 的引用。我想将地址对象与身份类一起存储，但在读取该对象时，我无法取回地址对象，并且它在我的主类中引发空指针异常下面我显​​示了与我的问题相关的所有代码，请执行必要的操作。

Address class--

package com.io.practice;
public class Address {

    String state;
    String country;

    public String getState() {
        return state;
    }

    public void setState(String state) {
        this.state = state;
    }

    public String getCountry() {
        return country;
    }

    public void setCountry(String country) {
        this.country = country;
    }

}


Identity Class--

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

import com.io.practice.Address;

public class Identity implements Serializable {

    private static final long serialVersionUID = 1L;
    transient Address address;
    int panCardId;

    public Address getAddress() {
        return address;
    }

    public void setAddress(Address address) {
        this.address = address;
    }

    public int getPanCardId() {
        return panCardId;
    }

    public void setPanCardId(int panCardId) {
        this.panCardId = panCardId;
    }

    public void writeObject(ObjectOutputStream os) throws IOException {
        os.defaultWriteObject();
        os.writeObject(address);

    }

    public void readObject(ObjectInputStream is) throws IOException, ClassNotFoundException {
        is.defaultReadObject();
        this.address=(Address) is.readObject();
    }

}

GraphTest main class--

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

import com.io.practice.Address;

public class GraphTest {

public static void main(String[] args) throws IOException, ClassNotFoundException {
    Identity id = new Identity();
    Address add = new Address();
    add.setCountry("Austrialia");
    add.setState("Sidney");
    id.setPanCardId(560100);
    id.setAddress(add);
    FileOutputStream fileOut = new FileOutputStream("D:/cgi.ser");
    ObjectOutputStream objectOut = new ObjectOutputStream(fileOut);
    objectOut.writeObject(id);
    objectOut.flush();
    objectOut.close();
    FileInputStream fileIn = new FileInputStream("D:/cgi.ser");
    ObjectInputStream objectIn = new ObjectInputStream(fileIn);
    Identity identity = (Identity) objectIn.readObject();
    System.out.println(identity.getPanCardId());
    System.out.println(identity.getAddress().getCountry());

}

}

System.out.println (identity.getAddress().getCountry()); 在这一行上得到空指针。如果可能，请更正代码。

提前致谢。

Answer 1

如果您想存储 Identity 的 Address 对象，则必须删除 transient 并将 Address 设置为 Serialized，这样在序列化 Identity 对象时就不会出现 NotSerializedException。