OutOfMemory exception when converting object to Json through Gson

Question

i am getting

java.lang.OutOfMemoryError

for some users (not always) when I convert a list of object to JSON using Gson. please tell me how to fix that.

@Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        if(myList != null && !myList.isEmpty()) {
            //exception at this line
            String myJson = new Gson().toJson(myList, myList.getClass());
            outState.putString(MY_LIST, myJson);
        }
        outState.putInt(NEXT_PAGE, getNextPage());
    }

myList is the list of my custom object and size of list is 400kb to 600kb

Answer 1

This will depend on the size of your list. Why don't you use streaming API https://sites.google.com/site/gson/streaming

To be more specific something like

public String writeListToJson(List myList) throws IOException {
    ByteArrayOutputStream byteStream =new ByteArrayOutputStream();
    OutputStreamWriter outputStreamWriter=new OutputStreamWriter(byteStream ,"UTF-8");
    JsonWriter writer = new JsonWriter(outputStreamWriter);
    writer.setIndent("  ");
    writer.beginArray();
    Gson gson = new GsonBuilder().excludeFieldsWithoutExposeAnnotation().setPrettyPrinting().create();
    for (Object o : myList) {
        gson.toJson(o, o.class, writer);
    }
    writer.endArray();
    writer.close();
    return byteStream.toString("UTF-8");
}

Answer 2

myList is the list of my custom object and size of list is 400kb to 600kb

Do NOT put that in the saved instance state Bundle . OutOfMemoryError is only one of your worries. You will crash with a FAILED BINDER TRANSACTION much of the time, as there is a 1MB limit on all simultaneous IPC transactions going on in your app.

If you are trying to deal with configuration changes, use something else to hold onto this information:

• Retained fragment
• onRetainNonConfigurationInstance()
• ViewModel from the Android Architecture Components
• etc.

If you are trying to deal with process termination/app restart, put an identifier in the saved instance state Bundle that will allow you to reload this list from a persistent store (database, plain file, etc.).