Added a method to get the timestamp of a chat's last message

Author: amyyong11

src/main/java/entities/chat/Chat.java

@@ -1,6 +1,7 @@
 package entities.chat;
 import entities.message.Message;
 
+import java.time.LocalDateTime;
 import java.util.ArrayList;
 // Chat is an abstract class
 public class Chat {
@@ -53,5 +54,17 @@ public void addtoconvHist(Message message){
         this.convHist.add(message);
     }
 
+    /**
+     * Return of the timestamp of a chat's last updated to conversation history. If conversation
+     * history is empty, return null
+     * @return timestamp of last update (or null if empty)
+     */
+    public LocalDateTime getLastUpdated(){
+        if (this.convHist.size() != 0) {
+            return this.convHist.get(this.convHist.size() - 1).getTimestamp();
+        }
+        return null;
+    }
+
 
 }

src/main/java/entities/chat/PrivateChat.java

@@ -45,10 +45,10 @@ public void setRecipientUsername(String recipientUsername) {
         this.recipientUsername= recipientUsername;
     }
 
-    public String getSendertUsername(){
+    public String getSenderUsername(){
         return this.senderUsername;
     }
-    public void setSendertUsername(String recipientUsername){
+    public void setSenderUsername(String recipientUsername){
         this.recipientUsername = recipientUsername;
     }
 

src/main/java/use_cases/chat_initiation_use_case/ChatInteractor.java

@@ -31,7 +31,7 @@ public void setRecipientUsername(String recipientUsername) {
     // Update the message history when the type in put in message txtfieled and click send button.
     public void setMessage(String content) {
         MsgFactory msgfactory = new MsgFactory("text");
-        privatechat.addtoconvHist(msgfactory.createMsg(privatechat.getSendertUsername(), content));
+        privatechat.addtoconvHist(msgfactory.createMsg(privatechat.getSenderUsername(), content));
     }