CODEWITHSUNDEEP
javaandroidandroid-studiobase64classnotfoundexception
Martin Lukas
Martin Lukas

Reputation: 314

ClassNotFoundException when trying to decode object from String

Alright so I've got this Android Studio app with user class

public class User{
   int age;
   String name;
   int yearOfBirth;
}

And then I've got this two methods

public static Object fromString(String s) throws IOException,ClassNotFoundException {
    byte [] data = Base64.getDecoder().decode(s);
    ObjectInputStream ois = new ObjectInputStream(new ByteArrayInputStream(data));
    Object o  = ois.readObject();
    ois.close();
    return o;
}

public static String toString(Serializable o) throws IOException {
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    ObjectOutputStream oos = new ObjectOutputStream(baos);
    oos.writeObject(o);
    oos.close();
    return Base64.getEncoder().encodeToString(baos.toByteArray());
}

So I create User object, convert it to String, save it to database on other device where I need to convert the object back to User object to change some stuff, convert to String again save to database and then be able to decode the User object in my app again.

Problem is when trying to decode the String on the server side I'm getting this exception

Exception in thread "main" java.lang.ClassNotFoundException: com.example.mikithenics.User

What could be the possible solution ? Any help is appreciated.

Upvotes: 0

Views: 409

Answers (1)

RennanP
RennanP

Reputation: 68

You can serialize this using Google Gson lib like this:

Gson gson = new Gson();

String jsonString = gson.toJson(userObject);

And deserialize like this:


Gson gson = new Gson();

User userObject = gson.fromJson(userJsonString, User.class);

To use Gson lib, put this in your app build.gradle file, inside dependencies:

implementation 'com.google.code.gson:gson:2.8.6'

Upvotes: 1

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