Core Concepts

This page describes some of the basic concepts you’ll encounter when using the Android Chat SDK.

Calls

Many SDK methods in the client and offline libraries return a Call object, which is a pending operation waiting to be executed.

Running Calls Synchronously

If you’re on a background thread, you can run a Call synchronously, in a blocking way, using the execute method:

// Only call this from a background thread
val messageResult = channelClient.sendMessage(message).execute()

// Only call this from a background thread
Result<Message> messageResult = channelClient.sendMessage(message).execute();

Running Calls Asynchronously

You can run a Call asynchronously, automatically scheduled on a background thread using the enqueue method. The callback passed to enqueue will be called on the UI thread.

// Safe to call from the main thread
channelClient.sendMessage(message).enqueue { result: Result<Message> ->
    if (result.isSuccess) {
        val sentMessage = result.data()
    } else {
        // Handle result.error()
    }
}

// Safe to call from the main thread
channelClient.sendMessage(message).enqueue((result) -> {
    if (result.isSuccess()) {
        Message sentMessage = result.data();
    } else {
        // Handle result.error()
    }
});

If you are using Kotlin coroutines, you can also await() the result of a Call in a suspending way:

viewModelScope.launch {
    // Safe to call from any CoroutineContext
    val messageResult = channelClient.sendMessage(message).await()
}

Error Handling

Actions defined in a Call return Result objects. These contain either the result of a successful operation or the error that caused the operation to fail.

You can check whether a Result is successful or an error - exactly one of the following will be true for each Result:

result.isSuccess
result.isError

result.isSuccess();
result.isError();

If the result was successful, you can get the contained data with data(). Otherwise, you can read error() and handle it appropriately.

if (result.isSuccess) {
    // Use result.data()
} else {
    // Handle result.error()
}

if (result.isSuccess()) {
    // Use result.data()
} else {
    // Handle result.error()
}

Calling data() on a failed Result or calling error() on a successful Result will throw an IllegalStateException.