In the Swing application
#How to live update chat screen when a new chat is entered to the ChatHistory context (Static list)
rain tapir
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rain tapir
There are two Actors Customer and Emplyee
Employee gets a UI to chat and also the customer
This is how the chats are managed across the application
public class ChatHistory {
private static Map<Actor, List<Chat>> chats = new HashMap<>();
public static Map<Actor, List<Chat>> getChats() {
return chats;
}
public static List<Chat> getChatsByActor(Actor actor) {
if (chats != null) {
return chats.get(actor);
}else{
return new LinkedList<>();
}
}
public static void addChat(Actor from,Actor to, String message) {
if (chats != null) {
if (chats.get(from) != null) {
List<Chat> messages = chats.get(from);
Chat chat = new Chat(from, to, message);
messages.add(chat);
chats.put(from, messages);
}
if (chats.get(from) == null) {
List<Chat> messages = new LinkedList<>();
Chat chat = new Chat(from, to, message);
messages.add(chat);
chats.put(from, messages);
}
}
}
}
To display the Chats for each Actor I use a method
which will load the chats
private void loadChat() {
chatScrollPane.removeAll();
rowCount = 0;
Map<Actor, List<Chat>> chats = ChatHistory.getChats();
for (Map.Entry<Actor, List<Chat>> entry : chats.entrySet()) {
Actor key = entry.getKey();
List<Chat> value = entry.getValue();
// if (ChatActorUtil.getName(key).equals(this.customer.getName())) {
if (key instanceof ChatCustomer) {
value.forEach(e -> {
if (e.getSender() instanceof ChatCustomer) {
ChatCustomer customer = (ChatCustomer) key;
if (customer.getName().equals(this.customer.getName())) {
chatScrollPane.add(new ToChatPanel(e.getMessage()));
rowCount++;
}
}
});
}
if (key instanceof ChatEmployee) {
ChatEmployee employee = (ChatEmployee) key;
value.forEach(e -> {
ChatCustomer customer = (ChatCustomer) e.getReceive();
if (customer.getName().equals(this.customer.getName())) {
chatScrollPane.add(new FromChatPanel("Employee", e.getMessage()));
rowCount++;
}
});
}
}
chatScrollPane.setLayout(new GridLayout(rowCount, 1));
chatScrollPane.revalidate();
chatScrollPane.repaint();
}
but the problem is this won't live update I have to manually refresh
or manually call the loadChats method
This is the mediator that manages the chats between actors
public class ConcreteMediator implements Mediator {
private List<Actor> actors;
public ConcreteMediator() {
this.actors = ActorStorage.getActorList();
}
public void addActor(Actor actor) {
ActorStorage.setActor(actor);
// this.actors.add(actor);
}
@Override
public void sendMessage(String message, Actor from, Actor to) {
if (from instanceof ChatEmployee) {
to.receiveMessage(message, from);
}
if (from instanceof ChatCustomer) {
to.receiveMessage(message, from);
}
ChatHistory.addChat(from, to, message);
}
}
fossil rover
when should what change?
Also, in most cases, you want to use ArrayList instead of LinkedList
rain tapir
when should what change?
When someone send a message, it should update the other user's UI
like how we chat in discord
rain tapir
no Just same instance
fossil rover
ah ok
rain tapir
One Swing application
fossil rover
Can you show the Chat class?
rain tapir
yeah
public class Chat {
private Actor sender;
private Actor receiver;
private String message;
public Chat(Actor sender, Actor receiver, String message) {
this.sender = sender;
this.receiver = receiver;
this.message = message;
}
public Actor getSender() {
return sender;
}
public void setSender(Actor sender) {
this.sender = sender;
}
public Actor getReceive() {
return receiver;
}
public void setReceive(Actor receive) {
this.receiver = receive;
}
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
}
This is the customer's UI after confirming the order
They get a Chat UI to chat
This is the UI what the employee get to chat with the customer
fossil rover
Can you show the receiveMessage method?
rain tapir
Concreate Mediator calls the receiveMessage method
public class ConcreteMediator implements Mediator {
private List<Actor> actors;
public ConcreteMediator() {
this.actors = ActorStorage.getActorList();
}
public void addActor(Actor actor) {
ActorStorage.setActor(actor);
// this.actors.add(actor);
}
@Override
public void sendMessage(String message, Actor from, Actor to) {
if (from instanceof ChatEmployee) {
to.receiveMessage(message, from);
}
if (from instanceof ChatCustomer) {
to.receiveMessage(message, from);
}
ChatHistory.addChat(from, to, message);
}
}
like inside the actors?
yah
public class ChatEmployee implements Actor {
private Mediator mediator;
private String name;
public ChatEmployee(Mediator mediator, String name) {
this.mediator = mediator;
this.name = name;
ConcreteMediator concreteMediator = (ConcreteMediator) this.mediator;
concreteMediator.addActor(this);
}
public String getName() {
return name;
}
@Override
public void sendMessage(String message, Actor to) {
mediator.sendMessage(message, this, to);
}
@Override
public void receiveMessage(String message, Actor from) {
ChatCustomer customer = (ChatCustomer)from;
System.out.println(this.name + " receives messages " + message+ " from "+customer.getName());
}
}
What about updating the UI there?
rain tapir
I didn't really nothing inside
rain tapir
public interface Actor {
void sendMessage(String message,Actor to);
void receiveMessage(String message, Actor from);
}
Why the
if (from instanceof ChatEmployee) {
to.receiveMessage(message, from);
}
if (from instanceof ChatCustomer) {
to.receiveMessage(message, from);
}
?
You can just do to.receiveMessage(message, from);
rain tapir
You can just do `to.receiveMessage(message, from);`
I thought about this so I thought it would be convenient in future to check the Actor instance
strange haloBOT
What about updating the UI there?
fossil rover
I think the best way is to have a reference to the UI in your ChatEmployee (and ChatCustomer)
rain tapir
yah yah
fossil rover
and update it from there
rain tapir
but wouldn't that couple the UI?
fossil rover
you can use an interface
For example, you could create a ChatUpdater interface
with a method addChatMessage
or actually use a listener
that's better
You create an interface like that
public interface ChatListener{
void onChatMessageReceived(Actor from, String message)
}
because of the performance issue ?
fossil rover
because of the performance issue ?
yeah
fossil rover
You create an interface like that
```java
public interface ChatListener{
void ...
and in your actors, you have a List<ChatListener>
and in the receiveMessage, you call the onChatMessageReceived of all listeners
fossil rover
To display the Chats for each Actor I use a method
which will load the chats
...
and the UI class can then do somethng like
customer.addChatListener((from, message) -> {
addMessageToUI(from, message);
});
ook alright
fossil rover
Would that work for you?
rain tapir
yah I will give a try and update you