Cannot evaluate the instance of anonymous class

[testforstephen]

Hi, I have a similar problem with internal field initializer.

import java.util.*;
public class RomanToInteger {
    public int romanToInt(String s) {
        var ri = new HashMap<Character,Integer>() {{ 
            put('I', 1);
        }};
        var c = ri.get(s.charAt(0)); // ri returns cannot evaluate
        return 0;
    }
}

Environment Operating System: Win 11 JDK version: openjdk version "11.0.12" 2021-07-20 Java extension version: Language Support for Java(TM) by Red Hat 0.40.1 Java Debugger extension version: 0.40.1 Visual Studio Code Version: 1.67.1 Commit: da15b6fd3ef856477bf6f4fb29ba1b7af717770d

Originally posted by @martinkunc in https://github.com/microsoft/vscode-java-debug/issues/754#issuecomment-1126981962

[github-actions[bot]]

Hi @testforstephen, 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.

During debugging, the console evaluates expressions in the context of the current frame—which, inside a double-brace initializer, is the anonymous class—so your local variable ri isn’t in scope there. Workarounds:

• Extract the map initialization outside the anonymous class:

var ri = new HashMap<Character, Integer>();
ri.put('I', 1);
var c = ri.get(s.charAt(0));

• Or use an immutable one-liner that doesn’t create an inner class:

var ri = Map.of('I', 1);
var c = ri.get(s.charAt(0));

These approaches ensure ri is visible to the debug console. You can still inspect the map via the VARIABLES view if you prefer.

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!