What methods are used for data exchange between separate processes?

Several methods are used for data exchange between separate processes (IPC) in Android:

• Intents — allow data transfer between components (Activity, Service) even in different processes.
• Content Providers — provide access to data and their exchange between applications through a standard interface.
• Binder — a low-level IPC mechanism in Android that allows calling methods of a remote object.
• Messenger — a wrapper around Binder for message exchange (Message) between processes.
• AIDL (Android Interface Definition Language) — used to define interfaces that can be called from another process.

Example of using Messenger for message exchange between processes:

// In the service, create a Handler and Messenger
class IncomingHandler extends Handler {
    @Override
    public void handleMessage(Message msg) {
        // handle message
    }
}
Messenger messenger = new Messenger(new IncomingHandler());

// In the client, send a message via Messenger
Message msg = Message.obtain(null, MSG_CODE);
clientMessenger.send(msg);