Question

I’d like to pass a custom Object from one activity to another, the Object consists of a String and a List of another custom Object which consists of an array of strings and an array of ints. I’ve read https://stackoverflow.com/a/2141166/830104, but then I’ve found this answer https://stackoverflow.com/a/7842273/830104. Which is better to use Bundle or Parcelable? What is the difference? When should I use this each?
Thanks for your replies,
Dan

Answer 1

Parcelable and Bundle are not exclusive concepts; you can even deploy both on your app at a time.

[1] Term Parcelable comes with Serialization concept in Java (and other high-level language such as C#, Python,…). It ensures that an object – which remains in RAM store – of such Parcelable class can be saved in file stream such as text or memory (offline status) then can be reconstructed to be used in program at runtime (online status).

In an Android application, within 2 independent activities (exclusively running – one starts then other will have to stop):

There will be NO pointer from current activity to refer to previous one and its members – because previous activity is stopped and cleared out form memory; so that to maintain object’s value passed to next activity (called from Intent) the object need to be parcelable (serializable).

[2] While Bundle is normally the Android concept, denotes that a variable or group of variables. If look into lower level, it can be considered as HashMap with key-value pairs.

Conclusion:

• Bundle is to store many objects with related keys, it can save any object in native types, but it doesn’t know how to save a complex object (which contains an ArrayList for example)

• Parcelable class is to ensure a complex instance of it can be serialized and de-serialized during runtime. This object can contains complex types such as ArrayList, HashMap, array, or struct,…

[UPDATED] – Example:

//Class without implementing Parcelable will cause error 
//if passing though activities via Intent
public class NoneParcelable
{
    private ArrayList<String> nameList = new ArrayList<String>();
    public NoneParcelable()
    {
        nameList.add("abc");
        nameList.add("xyz");            
    }
}

//Parcelable Class's objects can be exchanged 
public class GoodParcelable implements Parcelable
{
    private ArrayList<String> nameList = new ArrayList<String>();
    public GoodParcelable()
    {
        nameList.add("Can");
        nameList.add("be parsed");          
    }
    @Override
    public int describeContents()
    {
        return 0;
    }
    @Override
    public void writeToParcel(Parcel dest, int flags)
    {
        // Serialize ArrayList name here            
    }
}

In source activity:

NoneParcelable nonePcl = new NoneParcelable();
GoodParcelable goodPcl = new GoodParcelable();
int count = 100;

Intent i = new Intent(...);
i.putExtra("NONE_P",nonePcl);
i.putExtra("GOOD_P",goodPcl);
i.putExtra("COUNT", count);

In destination activity:

Intent i = getIntent();

//this is BAD:
NoneParcelable nP = (NoneParcelable)i.getExtra("NONE_P"); //BAD code

//these are OK:
int count = (int)i.getExtra("COUNT");//OK
GoodParcelable myParcelableObject=(GoodParcelable)i.getParcelableExtra("GOOD_P");// OK