Question

感觉我不理解某种基本的Java原则，但由于某种原因，我无法将我的类本身反序列化。当我在主类中运行它时，编译器捕获ClassNotFoundException。这是我的班级：

public class DataMaps<T> extends HashMap<String, T>{
private T t;

public void serialize() {
    try {
        FileOutputStream fos = new FileOutputStream("stopMap.ser");
        ObjectOutputStream oos = new ObjectOutputStream(fos);
        oos.writeObject(this);
        oos.close();
        fos.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

public HashMap getMap() {
    //De-serialize map stored in memory
    HashMap map = null;
    try
    {
        FileInputStream fis = new FileInputStream("stopMap.ser");
        ObjectInputStream ois = new ObjectInputStream(fis);
        map = (HashMap)ois.readObject(); //CLASSNOTFOUNDEXCEPTION
        ois.close();
        fis.close();
    } catch(IOException e) {
        e.printStackTrace();
    } catch(ClassNotFoundException e) {
        e.printStackTrace();
    }

    return map;
}

}

public class Main {

private Stops stop;
private DataMaps<Stops> stopsDataMap;
private String[] stopInfo;

public Main() {
    stopsDataMap = new DataMaps<Stops>();
    try {
        BufferedReader br = new BufferedReader(new FileReader("stops.txt"));
        String line = br.readLine();

        while((line = br.readLine()) != null){
            stopInfo = line.split(",");
            stop = new Stops(stopInfo[0], stopInfo[2], stopInfo[4], stopInfo[5]);
            stopsDataMap.put(stop.getStopId(), new Stops(stopInfo[2], stopInfo[4], stopInfo[5]));
            System.out.println(stop);
        }
        //stopsDataMap.serialize(); //commented out since the file exists

        System.out.println(stopsDataMap.getMap().toString()); //Produces the error

    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

public static void main(String args[]) {
    System.out.println("Hello");
    new Main();
}

}

首先，我将序列化地图强制转换为我创建的课程DataMaps和DataMaps<T>，但这些不起作用，所以我去尝试将序列化数据转换为HashMap我的类扩展但仍然得到错误。我不知道发生了什么，如果有人能指出这里的问题吗？

这是stacktrace：

java.lang.ClassNotFoundException: DataMaps
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:270)
at java.io.ObjectInputStream.resolveClass(ObjectInputStream.java:623)
at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1610)
at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1515)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1769)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1348)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:370)
at net.mastrgamr.gtfs.static_objects.DataMaps.getMap(DataMaps.java:40)
at net.mastrgamr.gtfs.Main.<init>(Main.java:33)
at net.mastrgamr.gtfs.Main.main(Main.java:43)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:134)

Answer 1

我想我可以从堆栈跟踪中看到问题。序列化发生在

net.mastrgamr.gtfs.static_objects.DataMaps.getMap

但例外是

java.lang.ClassNotFoundException: DataMaps

如果这是相同的DataMaps类，则会读取

java.lang.ClassNotFoundException: net.mastrgamr.gtfs.static_objects.DataMaps

您已将数据序列化到文件中，但随后将数据包添加到DataMaps，这使它们成为不同的类。

自定义类生成ClassNotFoundException

1 个答案: