fix: When chat event type is conversation.chat.completed, a NPE will …

[mifengjun]

fix: When chat event type is conversation.chat.completed, a NPE will be thrown;

Error occurred: Cannot invoke "com.coze.openapi.client.connversations.message.model.Message.getType()" because the return value of "com.coze.openapi.client.chat.model.ChatEvent.getMessage()" is null

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[coderabbitai]

Walkthrough

Adds a null-check before accessing event.getMessage() in the CONVERSATION_CHAT_COMPLETED event handler to prevent potential NullPointerException. The condition now verifies that the message is non-null alongside the MessageType.FOLLOW_UP check, maintaining existing control flow behavior.

Changes

Cohort / File(s)	Summary
Null-safety improvement example/src/main/java/example/chat/StreamChatExample.java	Added null-check before accessing event.getMessage() in the CONVERSATION_CHAT_COMPLETED branch alongside existing MessageType.FOLLOW_UP condition to prevent NullPointerException

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~5 minutes

• Single focused change with clear defensive programming intent
• Minimal scope affecting only one conditional branch
• Low risk of unintended side effects

Possibly related PRs

• chore: Update example to print follow up event #100: Modifies the same CONVERSATION_CHAT_COMPLETED handler in StreamChatExample.java for FOLLOW_UP message handling

Poem

🐰 A null-check hops into view,
Guarding messages tried and true,
No more crashes in the stream,
Safety's now the rabbit's dream! ✨

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	You can run @coderabbitai generate docstrings to improve docstring coverage.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title Check	✅ Passed	The title "fix: When chat event type is conversation.chat.completed, a NPE will …" is directly and fully related to the changeset. It clearly identifies the specific scenario (chat event type is conversation.chat.completed), the problem being addressed (NullPointerException/NPE), and the nature of the fix. The raw summary confirms the change adds a null-check in the CONVERSATION_CHAT_COMPLETED branch to prevent this exact NPE. The title is specific, descriptive, and accurately represents the primary change without vague language.
Description Check	✅ Passed	The description is directly related to the changeset and provides relevant context for the fix. It clearly states the problem: a NullPointerException is thrown when processing chat events with type conversation.chat.completed, and provides the specific error message indicating that getMessage() returns null. This aligns perfectly with the fix implemented, which adds a null-check before accessing event.getMessage(). The description is sufficiently detailed to explain the issue without being overly verbose.

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

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[coderabbitai]

Actionable comments posted: 1

🧹 Nitpick comments (2)

example/src/main/java/example/chat/StreamChatExample.java (2)

38-38: Remove the extra semicolon.

There's an unnecessary semicolon after the build() statement.

-            .build();
-    ;
+            .build();

---

78-83: Consider translating comments to English for consistency.

The comments on lines 78-80 are in Chinese, while all other comments in the file are in English. For codebase consistency and broader team accessibility, consider translating them.

-    // 为了防止程序立即退出，添加一个简单的等待
+    // Add a simple wait to prevent the program from exiting immediately
     try {
-      Thread.sleep(5000); // 等待5秒钟
+      Thread.sleep(5000); // Wait for 5 seconds
     } catch (InterruptedException e) {

📜 Review details

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between a1dad15 and 2d20b95.

📒 Files selected for processing (1)

• example/src/main/java/example/chat/StreamChatExample.java (1 hunks)

🧰 Additional context used

🪛 GitHub Actions: CI

example/src/main/java/example/chat/StreamChatExample.java

[error] 58-58: spotless check failed. The file has formatting violations detected by the Spotless Maven Plugin. Run 'mvn spotless:apply' to fix code style issues in this file.

🔇 Additional comments (1)

example/src/main/java/example/chat/StreamChatExample.java (1)

57-59: Review comment is based on incorrect assumption about null-safety for different event types.

The review suggests adding a null-check to CONVERSATION_MESSAGE_DELTA similar to CONVERSATION_CHAT_COMPLETED. However, examination of the PR and codebase shows:

• The PR specifically addresses null-safety for CONVERSATION_CHAT_COMPLETED events only (line 60-62)
• All four example files in the codebase (StreamChatExample.java, ChatWithImageExample.java, SubmitToolOutputExample.java, StreamWorkflowChatExample.java) consistently use event.getMessage().getContent() without null-checks for CONVERSATION_MESSAGE_DELTA events
• The API documentation indicates CONVERSATION_MESSAGE_DELTA is for "incremental message...usually when type=answer", suggesting the message field is guaranteed to be present

The null-safety issue addressed in the PR appears specific to CONVERSATION_CHAT_COMPLETED events, not CONVERSATION_MESSAGE_DELTA. Adding defensive checks to CONVERSATION_MESSAGE_DELTA is therefore unnecessary and would diverge from the established pattern across all examples.

Likely an incorrect or invalid review comment.

[coderabbitai]

⚠️ Potential issue | 🔴 Critical

Correct NPE fix, but address the formatting failure.

The null-check correctly prevents the NullPointerException described in the PR. The logic properly handles both cases: when a message exists with type FOLLOW_UP, and when the message is null (falling through to print token usage).

However, the pipeline indicates a Spotless formatting violation. Run mvn spotless:apply to fix the code style.

🤖 Prompt for AI Agents

In example/src/main/java/example/chat/StreamChatExample.java around line 61 the
null-check for event.getMessage() fixes the NPE but the file fails Spotless
formatting; run mvn spotless:apply (or your project's formatter) and commit the
formatted changes so the formatting violation is resolved.