Merge pull request #172 from johnoliver/fix-chat-history

Fix ChatHistory.getLast

Author: johnoliver

semantickernel-api/src/main/java/com/microsoft/semantickernel/services/chatcompletion/ChatHistory.java

@@ -5,13 +5,11 @@
 import com.microsoft.semantickernel.services.chatcompletion.message.ChatMessageTextContent;
 import java.nio.charset.Charset;
 import java.util.ArrayList;
-import java.util.Collection;
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Optional;
 import java.util.Spliterator;
-import java.util.concurrent.ConcurrentLinkedQueue;
 import java.util.function.Consumer;
 import javax.annotation.Nullable;
 
@@ -20,7 +18,7 @@
  */
 public class ChatHistory implements Iterable<ChatMessageContent<?>> {
 
-    private final Collection<ChatMessageContent<?>> chatMessageContents;
+    private final List<ChatMessageContent<?>> chatMessageContents;
 
     /**
      * The default constructor
@@ -35,7 +33,7 @@ public ChatHistory() {
      * @param instructions The instructions to add to the chat history
      */
     public ChatHistory(@Nullable String instructions) {
-        this.chatMessageContents = new ConcurrentLinkedQueue<>();
+        this.chatMessageContents = Collections.synchronizedList(new ArrayList<>());
         if (instructions != null) {
             this.chatMessageContents.add(
                 ChatMessageTextContent.systemMessage(instructions));
@@ -48,7 +46,8 @@ public ChatHistory(@Nullable String instructions) {
      * @param chatMessageContents The chat message contents to add to the chat history
      */
     public ChatHistory(List<? extends ChatMessageContent<?>> chatMessageContents) {
-        this.chatMessageContents = new ConcurrentLinkedQueue<>(chatMessageContents);
+        this.chatMessageContents = Collections
+            .synchronizedList(new ArrayList<>(chatMessageContents));
     }
 
     /**
@@ -70,7 +69,7 @@ public Optional<ChatMessageContent<?>> getLastMessage() {
             return Optional.empty();
         }
         return Optional
-            .of(((ConcurrentLinkedQueue<ChatMessageContent<?>>) chatMessageContents).peek());
+            .of(chatMessageContents.get(chatMessageContents.size() - 1));
     }
 
     /**