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ClassCastException in Inheritance - Why?

By : Pedro Adelino
Date : September 15 2020, 11:00 AM
like below fixes the issue The compiler infers the type returned by al.makeParent() according to the a() method being chosen by the method overloading resolution.
Since the method overloading resolution first considers candidates that don't have vararg arguments, only the public void a(List ss) overload is considered, and therefore that's the chosen overload.
code :
class Child extends Parent implements List<ParentI>

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JPA Inheritance entitymanager.find produces ClassCastException

By : user2237852
Date : March 29 2020, 07:55 AM
To fix this issue I know that this has been a problem in Hibernate during a long time, see for example:
ClassCastException cglib lazy loading JPA: instanceof vs. hibernate proxy: when is it safe? How to Avoid ClassCastExceptions when using Hibernate Proxied Objects)
code :
[INFO] +- org.hibernate:hibernate-entitymanager:jar:3.4.0.GA:compile
[INFO] |  +- org.hibernate:ejb3-persistence:jar:1.0.2.GA:compile
[INFO] |  +- org.hibernate:hibernate-commons-annotations:jar:3.1.0.GA:compile
[INFO] |  +- org.hibernate:hibernate-annotations:jar:3.4.0.GA:compile
[INFO] |  +- org.hibernate:hibernate-core:jar:3.3.0.SP1:compile
[INFO] |  |  +- antlr:antlr:jar:2.7.6:compile
[INFO] |  |  \- commons-collections:commons-collections:jar:3.1:compile
[INFO] |  +- org.slf4j:slf4j-api:jar:1.5.10:compile
[INFO] |  +- dom4j:dom4j:jar:1.6.1:compile
[INFO] |  |  \- xml-apis:xml-apis:jar:1.0.b2:compile
[INFO] |  \- javax.transaction:jta:jar:1.1:compile
[INFO] \- org.hibernate:hibernate-cglib-repack:jar:2.1_3:compile

Java inheritance downcast ClassCastException

By : Hadi Valipour
Date : March 29 2020, 07:55 AM
To fix this issue All B's are A's, by inheritance. But not all A's are B's. This particular instance isn't, hence the runtime exception.

ClassCastException Object Inheritance with Retrofit

By : Polngpole Tharmmakol
Date : March 29 2020, 07:55 AM
This might help you Yes, the issue is the gson always creates the type in the retrofit call. You need to provide a custom deserializer to figure out the object type based on your type field. Here is a sketch of what that might look like.
code :
public class ModiaPojoDeserializer implements JsonDeserializer<Model> {

    private static final String TYPE_FIELD = "type";
    private static final String IMAGE_TYPE = "image";
    private static final String VIDEO_TYPE = "video";

    public Model deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
        if (json.isJsonObject() && json.getAsJsonObject().has(TYPE_FIELD)) {
            JsonObject jsonObject = json.getAsJsonObject();
            final String type = jsonObject.get(TYPE_FIELD).getAsString();
            if (VIDEO_TYPE.equals(type)) {
                return context.deserialize(json, VideoPojo.class);
            } else if (IMAGE_TYPE.equals(type)) {
                return context.deserialize(json, ImagePojo.class);
            } // ...
            // If you need to deserialize as MediaPojo,
            // deserialize without the current context 
            // or you will infinite loop
            return new Gson().fromJson(json, typeOfT);

        } else {
            // Return a blank object on error, could use null
            return new MediaPojo();
 Gson gson = new GsonBuilder()
     .registerTypeAdapter(MediaPojo.class, new MediaPojoDeserializer())
RestAdapter restAdapter = new RestAdapter.Builder()
    .setConverter(new GsonConverter(gson))

ClassCastException when intercept Parcelable with inheritance

By : Abeeha Aamir
Date : March 29 2020, 07:55 AM
I wish this help you Consider the following scenario(using the same classes, a is super, b is child):
You can do:
code :
A a = new B();
B b = new A();
B b = new A()

ClassCastException with Gson and class inheritance from generic ArrayList

By : fhatfiel
Date : March 29 2020, 07:55 AM
Hope that helps OK, I have just written a custom adapter and it works fine. It's going to be a bit more complicated with the real code, though, but at least I know who to solve this.
Here's the code:
code :
import com.google.gson.GsonBuilder;
import com.google.gson.TypeAdapter;
import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonWriter;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;

class IntegerArrayList extends ArrayList<Integer> {
    String customField = "test";

    public IntegerArrayList(Integer... items) {

    public static IntegerArrayList fromJson(String json) {
        IntegerArrayList integerArrayList = new GsonBuilder()
                .registerTypeAdapter(IntegerArrayList.class, new JsonAdapter())
                .fromJson(json, IntegerArrayList.class);
        return integerArrayList;

    public String toJson() {
        return new GsonBuilder()
                .registerTypeAdapter(IntegerArrayList.class, new JsonAdapter())
                .toJson(this, IntegerArrayList.class);

    public static class JsonAdapter extends TypeAdapter<IntegerArrayList> {
        public void write(JsonWriter out, IntegerArrayList value) throws IOException {
            for (Integer v : value) {

        public IntegerArrayList read(JsonReader in) throws IOException {
            IntegerArrayList rtn = new IntegerArrayList();
            while (in.hasNext()) {
                switch (in.nextName()) {
                    case "customField":
                        rtn.customField = in.nextString();
                    case "items":
                        while (in.hasNext()) {
            return rtn;

public class GsonTest {
    public static void main(String[] args) {
        IntegerArrayList integerArrayList = new IntegerArrayList(1, 2, 3, 4, 5);
        String json = integerArrayList.toJson();
        IntegerArrayList integerArrayList1 = IntegerArrayList.fromJson(json);
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