How to handle WebSocket disconnection and reconnection in Kotlin Android

How to handle WebSocket disconnection and reconnection in Kotlin Android.

Here's a step-by-step tutorial on how to handle WebSocket disconnection and reconnection in Kotlin Android:

Step 1: Add the necessary dependencies

To work with WebSocket in Kotlin Android, you need to add the following dependency to your app-level build.gradle file:

implementation 'org.java-websocket:Java-WebSocket:1.4.0'

Step 2: Create a WebSocket connection class

Create a WebSocketConnection class to handle the WebSocket connection and its events. This class will handle the connection, disconnection, and reconnection logic. Here's an example implementation:

import org.java_websocket.client.WebSocketClient
import org.java_websocket.handshake.ServerHandshake
import java.net.URI

class WebSocketConnection(private val serverUri: URI) : WebSocketClient(serverUri) {

    override fun onOpen(handshakedata: ServerHandshake?) {
        // Handle WebSocket connection opened event
        println("WebSocket connection opened")
    }

    override fun onClose(code: Int, reason: String?, remote: Boolean) {
        // Handle WebSocket connection closed event
        println("WebSocket connection closed: $reason")
        
        // Reconnect to the WebSocket server
        reconnect()
    }

    override fun onMessage(message: String?) {
        // Handle WebSocket message received event
        println("Received message: $message")
    }

    override fun onError(ex: Exception?) {
        // Handle WebSocket error event
        println("WebSocket error: ${ex?.message}")
    }

    private fun reconnect() {
        // Implement your reconnection logic here
        // You can use a timer or exponential backoff algorithm to control the reconnection attempts
        println("Reconnecting to WebSocket server...")
        
        // Example: Reconnect after 5 seconds
        Thread.sleep(5000)
        connect()
    }
}

Step 3: Connect to the WebSocket server

Create an instance of the WebSocketConnection class and connect to the WebSocket server. You can do this in your activity or fragment where you want to establish the WebSocket connection. Here's an example:

val serverUri = URI("wss://your-websocket-server-url")
val webSocketConnection = WebSocketConnection(serverUri)
webSocketConnection.connect()

Step 4: Handle WebSocket disconnection and reconnection

With the WebSocketConnection class, you can handle WebSocket disconnection and reconnection events. The class's onClose method is called when the WebSocket connection is closed. In this method, you can implement your reconnection logic. The example implementation uses a simple reconnection after a fixed time delay. You can customize it based on your requirements.

Step 5: Clean up resources

To clean up resources properly, override the onDestroy or onStop method in your activity or fragment, and call the close method of the WebSocketConnection object. This will close the WebSocket connection and release any resources associated with it. Here's an example:

override fun onDestroy() {
    super.onDestroy()
    webSocketConnection.close()
}

That's it! You've now learned how to handle WebSocket disconnection and reconnection in Kotlin Android. You can customize the reconnection logic based on your specific requirements.