How to intercept message from a channel?

Hi,

I'd like to know how will I able to intercept messages from a channel.

this code can only intercept message sent/received to a specific user.
@OverRide
public void onTLUpdateNewMessageCustom(TLUpdateNewMessage update) {
onTLAbsMessageCustom(update.getMessage());

}

@OverRide
public void onTLUpdateNewMessageCustom(TLUpdateupdate) {
onTLAbsMessageCustom(update.getMessage());

}

I tried to extend this method to getMessage but it is empty.

@OverRide
protected void onTLUpdateMessageIdCustom(TLUpdateMessageId update) {

}

Thank you.