JetBrains/intellij-community · error · ConfigurationException

''{0}'' is invalid extracted class name

Error message

''{0}'' is invalid extracted class name

What it means

ExtractClassDialog.canRun throws ConfigurationException (JavaBundle key invalid.extracted.class.name) when the 'class name' field of the Extract Class dialog is empty or fails PsiNameHelper.isIdentifier — i.e. it is not a valid Java identifier (keyword, illegal character, digit-first, or empty).

Source

Thrown at java/java-impl-refactorings/src/com/intellij/refactoring/extractclass/ExtractClassDialog.java:183

      return;
    }
    invokeRefactoring(processor);
  }

  @Override
  protected void canRun() throws ConfigurationException {
    final Project project = sourceClass.getProject();
    final PsiNameHelper nameHelper = PsiNameHelper.getInstance(project);
    final List<PsiMethod> methods = getMethodsToExtract();
    final List<PsiField> fields = getFieldsToExtract();
    final List<PsiClass> innerClasses = getClassesToExtract();
    if (methods.isEmpty() && fields.isEmpty() && innerClasses.isEmpty()) {
      throw new ConfigurationException(LangBundle.message("dialog.message.nothing.found.to.extract"));
    }

    final String className = getClassName();
    if (className.isEmpty() || !nameHelper.isIdentifier(className)) {
      throw new ConfigurationException(JavaBundle.message("invalid.extracted.class.name", className));
    }

    /*final String packageName = getPackageName();
    if (packageName.length() == 0 || !nameHelper.isQualifiedName(packageName)) {
      throw new ConfigurationException("\'" + packageName + "\' is invalid extracted class package name");
    }*/
    for (PsiClass innerClass : innerClasses) {
      if (className.equals(innerClass.getName())) {
        throw new ConfigurationException(
          JavaBundle.message("extracted.class.should.have.unique.name", className));
      }
    }
  }

  public @NotNull String getPackageName() {
    return packageTextField.getText().trim();
  }

View on GitHub (pinned to be881553f2)

Solutions

1. Enter a non-empty identifier: letters/digits/underscore/'$', not starting with a digit, not a Java keyword.
2. Trim accidental spaces; CamelCase names like 'ExtractedData' are fine.
3. Pick a unique name relative to the source class's inner classes to also pass the subsequent uniqueness check.

Example fix

# before:
Class name: extracted-data

# after:
Class name: ExtractedData

String name = getClassName();
if (name.isEmpty() || !PsiNameHelper.getInstance(project).isIdentifier(name)) {
  // highlight the class-name field with 'not a valid Java identifier'
}

try { dialog.canRun(); } catch (ConfigurationException e) { /* fix the class name and retry */ }

When it happens

Trigger: Leaving the class-name field empty; entering '1Class', 'my-class', 'new', or 'My Class' (space) in the name field of the Extract Class dialog.

Common situations: Users typing display-style names with spaces or dashes; names colliding with Java keywords; auto-focus lost and OK pressed with the field untouched; pasted names with whitespace or trailing punctuation.

Related errors

• Nothing found to extract
• Extracted class should have unique name. Name ''{0}'' is alr
• ''{0}'' is invalid field name for delegation
• Invalid package name: {0}
• ''{0}'' is invalid parameter name

AI-assisted analysis of JetBrains/intellij-community@be881553f2 (2026-08-14). Data as JSON: /api/errors/202bba619f2d4663. Report an issue: GitHub.