Debugging in one-line lambdas does not work

[fhuonder]

Hi

My versions:

• vscode: 1.99.2
• vscode-java-debug: 0.58.1
• Language Support for Java(TM) by Red Hat: 1.41.1
• JDK 24
• vscode devcontainer
• Maven project

I cannot debug one-line lambdas.

This is how the code looks like as soon as I start the application:

As you can see, the two breakpoints where the lambda is a one-liner are grayed out (unverified breakpoint).
The execution does not stop there but it stops at the other breakpoints.
The one-liner breakpoints are created as inline breakpoints.

My assumption is that this is a bug.

Here the code to take and paste somewhere:

public String createMessage() {
    return Stream.of("Hello", " World", " - ", "What's", " up?")
    .map(token -> token + "1")
    .map(token -> {return token + "2";})
    .map(token -> {
        String result = token.substring(0, token.length() - 2);
        return result;
    })
    .collect(Collectors.joining());
}

Would be nice if this could be fixed or if someone can tell me what I'm doing wrong.

[chagong]

Florian Huonder (@fhuonder) can you recheck this issue? I can hit the breakpoints.

[fhuonder]

Hi,

Sorry for my late response.
The (inline) breakpoint on line 13 .map(token -> token + "1") is still not hit.

The others work.

I am on version 0.58.2.

Regards,
Florian

[github-actions]

Hi Florian Huonder (@fhuonder), I'm an AI Support assistant here to help with your issue. While the team reviews your request, I wanted to provide some possible tips and documentation that might help you in the meantime.

Workaround

• VS Code’s Java debugger currently ignores column information for inline (one-line) lambdas, so breakpoints on those lambdas remain unverified.
• Expand your lambda into a multi-line block and set the breakpoint on its own line. For example:

  .map(token -> {
      String temp = token + "2";
      return temp;
  })

Duplicate issue

• Debugging in one-line lambdas does not work: Debugging in one-line lambdas does not work java-debug#588

Other references with high confidence

• add support for lambda breakpoints (inline column ignored): add support for lambda breakpoints #1160 (comment)
• Breakpoint with inline lambdas work only with last one: Breakpoint with inline lambdas work only with last one #1410

Other references with low confidence

None

The team will respond to your issue shortly. I hope these suggestions are helpful in the meantime. If this comment helped you, please give it a 👍. If the suggestion was not helpful or incorrect, please give it a 👎. Your feedback helps us improve!