How to send an object from one Android Activity to

Question

How can I pass an object of a custom type from one Activity to another using the putExtra() method of the class Intent?

Answer 1

If you're just passing objects around then Parcelable was designed for this. It requires a little more effort to use than using Java's native serialization, but it's way faster (and I mean way, WAY faster).

From the docs, a simple example for how to implement is:

// simple class that just has one member property as an example
public class MyParcelable implements Parcelable {
    private int mData;

    /* everything below here is for implementing Parcelable */

    // 99.9% of the time you can just ignore this
    @Override
    public int describeContents() {
        return 0;
    }

    // write your object's data to the passed-in Parcel
    @Override
    public void writeToParcel(Parcel out, int flags) {
        out.writeInt(mData);
    }

    // this is used to regenerate your object. All Parcelables must have a CREATOR that implements these two methods
    public static final Parcelable.Creator<MyParcelable> CREATOR = new Parcelable.Creator<MyParcelable>() {
        public MyParcelable createFromParcel(Parcel in) {
            return new MyParcelable(in);
        }

        public MyParcelable[] newArray(int size) {
            return new MyParcelable[size];
        }
    };

    // example constructor that takes a Parcel and gives you an object populated with it's values
    private MyParcelable(Parcel in) {
        mData = in.readInt();
    }
}

Observe that in the case you have more than one field to retrieve from a given Parcel, you must do this in the same order you put them in (that is, in a FIFO approach).

Once you have your objects implement Parcelable it's just a matter of putting them into your Intents with putExtra():

Intent i = new Intent();
i.putExtra("name_of_extra", myParcelableObject);

Then you can pull them back out with getParcelableExtra():

Intent i = getIntent();
MyParcelable myParcelableObject = (MyParcelable) i.getParcelableExtra("name_of_extra");

If your Object Class implements Parcelable and Serializable then make sure you do cast to one of the following:

i.putExtra("parcelable_extra", (Parcelable) myParcelableObject);
i.putExtra("serializable_extra", (Serializable) myParcelableObject);

Answer 2

You'll need to serialize your object into some kind of string representation. One possible string representation is JSON, and one of the easiest ways to serialize to/from JSON in android, if you ask me, is through Google GSON.

In that case you just put the string return value from (new Gson()).toJson(myObject); and retrieve the string value and use fromJson to turn it back into your object.

If your object isn't very complex, however, it might not be worth the overhead, and you could consider passing the separate values of the object instead.

Answer 3

if your object class implements Serializable, you don't need to do anything else, you can pass a serializable object.
that's what i use.

Answer 4

I use Gson with its so powerful and simple api to send objects between activities,

Example

// This is the object to be sent, can be any object
public class AndroidPacket {

    public String CustomerName;

   //constructor
   public AndroidPacket(String cName){
       CustomerName = cName;
   }   
   // other fields ....


    // You can add those functions as LiveTemplate !
    public String toJson() {
        Gson gson = new Gson();
        return gson.toJson(this);
    }

    public static AndroidPacket fromJson(String json) {
        Gson gson = new Gson();
        return gson.fromJson(json, AndroidPacket.class);
    }
}

2 functions you add them to the objects that you want to send

Usage

Send Object From A to B

    // Convert the object to string using Gson
    AndroidPacket androidPacket = new AndroidPacket("Ahmad");
    String objAsJson = androidPacket.toJson();

    Intent intent = new Intent(A.this, B.class);
    intent.putExtra("my_obj", objAsJson);
    startActivity(intent);

Receive In B

@Override
protected void onCreate(Bundle savedInstanceState) {        
    Bundle bundle = getIntent().getExtras();
    String objAsJson = bundle.getString("my_obj");
    AndroidPacket androidPacket = AndroidPacket.fromJson(objAsJson);

    // Here you can use your Object
    Log.d("Gson", androidPacket.CustomerName);
}

I use it almost in every project i do and I have no performance issues.

Answer 5

You can send serializable object through intent

// send where details is object
ClassName details = new ClassName();
Intent i = new Intent(context, EditActivity.class);
i.putExtra("Editing", details);
startActivity(i);


//receive
ClassName model = (ClassName) getIntent().getSerializableExtra("Editing");

And 

Class ClassName implements Serializable {
} 

Answer 6

implement serializable in your class

        public class Place implements Serializable{
        private int id;
        private String name;

        public void setId(int id) {
           this.id = id;
        }
        public int getId() {
           return id;
        }
        public String getName() {
           return name;
        }

        public void setName(String name) {
           this.name = name;
        }
        }

Then you can pass this object in intent

     Intent intent = new Intent(this, SecondAct.class);
     intent.putExtra("PLACE", Place);
     startActivity();

int the second activity you can get data like this

     Place place= (Place) getIntent().getSerializableExtra("PLACE");

But when the data become large,this method will be slow.