如何通过 Intent 将对象发送到 Android 中的另一个 Activity？

Question

I am developing in Android. I tried sending a Bluetooth object to another Activity.

Code :

    BluetoothSocket btSocket;

Intent i = new Intent(ActivityA.this, ActivityB.class);
i.putExtra(EXTRA_BT_SOCKET,btSocket);
startActivity(i);

But it seems to be not working and it shows an error like:

Cannot resolve method 'putExtra(java.lang.String, android.bluetooth.BluetoothSocket)

How to send the Bluetooth object via intent to another Activity in Android?

Thanks in advance.

Answer 1

You can't put a BluetoothSocket instance in a Bundle or pass it as an Intent "extra" like that. This would require serializing and deserializing the object, which would make a copy of the object. You can't copy a socket like that. What you want to do is just share the object between multiple activities. The easiest way to do that is to put a reference to the object in a public static variable somewhere and just use it from all activities that need access.

Answer 2

Use the following to send and retrieve objects:

//To pass: intent.putExtra("MyClass", obj);

// To retrieve object in second Activity
getIntent().getSerializableExtra("MyClass");

Answer 3

Use a helper class

public class BluetoothSocketHelper implements Serializable {

    public BluetoothSocket btSocket;

    //Constructor + getter/setters
}

Sending from ActivityA:

BluetoothSocketHelper bluetoothSocketHelper;

Intent i = new Intent(ActivityA.this, ActivityB.class);
i.putExtra(DeviceListActivity.EXTRA_ADDRESS, address);
i.putExtra(EXTRA_BT_SOCKET, bluetoothSocketHelper);
startActivity(i);

Then in ActivityB:

private BluetoothSocket btSocket;

if(getIntent().getExtras()!=null){
    bluetoothSocketHelper = (BluetoothSocketHelper) getIntent().getSerializableExtra(EXTRA_BT_SOCKET);
    btSocket = (BluetoothSocket) bluetoothSocketHelper.getBluetoothSocket();
}

Answer 4

Hey @Wun I know it is too late but I found a simple way to do that, in your first activity just start the activity and send your object:

Intent intent = new Intent(this, Second.class);
intent.putExtra("rideId", yourObject);
startActivity(intent);

And in the Second Activity:

String id = extras.getString("rideId");
try {
   JSONObject mJsonObject = new JSONObject(id);
} catch (JSONException e) {
   e.printStackTrace();
}

Answer 5

you can pass it as a bundle through the intent

 Bundle bundle = new Bundle();
 bundle.putParcelable("yourObject key name", YOUR_OBJECT); //make YOUR_OBJECT implement parcelable
 Intent intents = new Intent(ActivityA.this, ActivityB.class);
 intents.putExtra(Constants.BUNDLE_DATA, bundle);
 startActivity(intents);

At recieving end (ActivityB.class)

if (intent != null && intent.hasExtra(Constants.BUNDLE_DATA)) {
        Bundle bundle = intent.getBundleExtra(Constants.BUNDLE_DATA);
        if (bundle != null && bundle.containsKey(yourObject key name)) {
            Object yourObject = bundle.getParcelable(yourObject keyname);
    }