Develop Reference

Sending objects between activities

There are two activity classes in my project and a third class which is subclass of Thread.
Thread Class implements Bluetooth Socket which isn't Parcelable.
First Activity starts the Second Activity using startActivityforResult()
Second Activity creates an object of the Thread class and starts the thread.
I need to pass an object reference of the Thread object from Second Activity to First Activity's onActivityResult() so that I can access Thread object from the first activity.
How can I achieve this?

You have a few options.
You can either break down your object into simple data types and put those values as extras on the intent that you pass back with setResult(), do do so you'd use intent.putExtra(key, value)
Or you can make your data object implement the Parcelable interface so that you can add the data object directly to the intent.
the code to do the latter would look something like this
Intent resultIntent = new Intent();
resultIntent.putExtra("resultObject", mObj);
setResult(ACTION_OK, resultIntent);
then inside your onActivityResult you can pull it out like this:
data.getParcelableExtra("resultObject");
For the latter method to work you need to correctly implement parcelable with your data object. The former method does not require this however, since you'll be passing back simple values only. You'd then have to take those simple values and "re-inflate" the data object on the other side.

I think the best way to achieve this would be to use a singleton. You can only store primitives in Shared Preferences and Bundles. Here is a great reference for creating a singleton.
http://www.javaworld.com/javaworld/jw-04-2003/jw-0425-designpatterns.html

Android - Problem with the Serializable interface

I have been using the Serializable interface to pass an object from one activity to another. I am using putExtra on the sender side and getSerializable on the receiver side. Everything works fine but I have received (for the first time) the following error report:
java.lang.RuntimeException: Parcelable encountered IOException reading
a Serializable object
I don't understand why this exception has been generated since I am using getSerializable and not getParcelable.
I know that I should implement the Parcelable interface instead because it has been designed specifically for Android (and that's what I will end up doing) but I want to understand why I am getting this error.
Thanks!

Parcelable is mentioned in this error because an Intent you send from one Activity to another has a Bundle inside and this Bundle is Parcelable. When you call Intent.putExtra() this extra is added to the inner Bundle. When Intent is passed between activities its Bundle is converted to and from a byte array and so is your Serializable object.
But I don't know why this error occurs. Maybe it's because of some bug in writeObject()/readObject() implementation.

Passing arraylist in intent from one activity to another

I have a class 'Product' and i need to pass the arraylist of 'Product' objects from one activity to another.
I read that i can do so by making my Product class as Parcelable and use : putParcelableArrayListExtra (String name, ArrayList value).
In my app, i need to pass arraylists of objects from one activity to another. In this case, i need to make all those classes as parcelable and implement the interface methods.
Is this the correct way to solve the problem? Is there any other way to send the list of objects in intents?
Thanks..

Yes, the correct way is to use Parcelable or do the serialization to another kind of primitive object that you can put to Intent's extras

Android: how to use data passed from parent activity in a sub activity?

When we want to pass data from an activity to a sub activity we use the
intent.pushextra()
method and pass the request code and any additional data.
now in the subactivity how can I get the additional data or the request code.
is there any event handler that handles this ?
thanks

You use intent.putExtra() to put data in the intent, then in the sub activity's onCreate() use getIntent().getExtras() or getIntent().getXXXExtra() methods.
For example for retrieving a String you would use: getStringExtra()

Android: Serializable Intent

I have an object that has (among other things) a list of Intents. I want to pass this object as an extra to an Intent. However, the Intent class is not serializable, it is just "Parcelable".
I assume that Parcelable is the android version of Serializable, but I'd rather not have to write my own serialization code for my class, and Parcelable seems to require that.
Anyone have any solutions to this other than just reimplementing the Intent as a serializable class?

You can put a Parcelable in an Intent extra, and an Intent is already Parcelable. All you need to do is make your object Parcelable and you are set.

Another Route you can take:
make your list of intents transient(not included in a serializable),
then pass it as a parcelable array via Intent.putExtra(String key, Parcelable[] value).
The receiving class can then recreate your Object.