How to serialize & deserialize response object of Httpclient into byte array

Question

I want to serialize and deserialize http response object of Apache, okhttp client etc.

I am unable to use ->

1. Java Serializable as response objects of both the clients don't implement serializable interface.
2. Jackson because response object doesn't have no-arg constructor hence shows below error while deserialization.

com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `org.example.Student` (no Creators, like default constructor, exist): cannot deserialize from Object value (no delegate- or property-based Creator)

3. Gson due to out of memory error:

(ApacheClient is used below)

Serialization:

       Gson gson = new GsonBuilder().setPrettyPrinting().create();
       ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
       OutputStreamWriter writer = new OutputStreamWriter(outputStream);
       gson.toJson(httpResponse, writer);
       writer.flush();

Deserialization:

       byte[] data = outputStream.toByteArray();
       ByteArrayInputStream inputStream = new ByteArrayInputStream(data);
       InputStreamReader reader = new InputStreamReader(inputStream);
       HttpResponse res = gson.fromJson(reader, HttpResponse.class);
       System.out.println("HttpResponse-> " + EntityUtils.toString(res.getEntity()));

Error:

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
    at java.util.Arrays.copyOf(Arrays.java:3332)
    at java.lang.AbstractStringBuilder.ensureCapacityInternal(AbstractStringBuilder.java:124)
    at java.lang.AbstractStringBuilder.append(AbstractStringBuilder.java:448)
    at java.lang.StringBuffer.append(StringBuffer.java:276)
    at java.io.StringWriter.write(StringWriter.java:101)
    at com.google.gson.stream.JsonWriter.newline(JsonWriter.java:602)
    at com.google.gson.stream.JsonWriter.beforeValue(JsonWriter.java:646)
    at com.google.gson.stream.JsonWriter.value(JsonWriter.java:532)
    at com.google.gson.internal.bind.TypeAdapters$5.write(TypeAdapters.java:189)
    at com.google.gson.internal.bind.TypeAdapters$5.write(TypeAdapters.java:173)
    at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:69)
    at com.google.gson.internal.bind.ArrayTypeAdapter.write(ArrayTypeAdapter.java:95)
    at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:69)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:127)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:245)
    at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:69)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:127)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:245)
    at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:69)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:127)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:245)
    at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:69)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:127)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:245)
    at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:69)
    at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.write(CollectionTypeAdapterFactory.java:97)
    at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.write(CollectionTypeAdapterFactory.java:61)
    at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:69)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:127)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:245)
    at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:69)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:127)

Answer 1

• The first question is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `org.example.Student` (no Creators, like default constructor, exist): cannot deserialize from Object value (no delegate- or property-based Creator) shows that org.example.Student class should declared a default constructor. So what is the default constructor? Okay, it's just a non-args constructer.

• Java Memory Analyze to analysis the JVM memory usage.