JetBrains/intellij-community · warning · ConfigurationException

'' '' is invalid parameter name

Error message

''{0}'' is invalid parameter name

What it means

Thrown by IntroduceParameterDialog.canRun() (java/java-impl-refactorings/src/com/intellij/refactoring/introduceParameter/IntroduceParameterDialog.java:302) when the user-typed parameter name fails PsiNameHelper.isIdentifier(). It is a pre-flight validation of the Introduce Parameter refactoring: the dialog refuses to run until the name is a valid Java identifier for the project's language level. The ConfigurationException is caught by the refactoring dialog framework, which shows the message and keeps the dialog open.

Solutions

1. Edit the Name field in the Introduce Parameter dialog to a valid Java identifier (letters, digits, '_', '$', not starting with a digit, not a keyword) and re-run.
2. Check the module's language level if you believe the name is legal (e.g. contextual keywords) — PsiNameHelper validation is language-level sensitive.
3. If driving the refactoring programmatically, validate the name with PsiNameHelper.getInstance(project).isIdentifier(name) before invoking the handler.

Example fix

// before
new IntroduceParameterHandler().invoke(project, editor, file, null);
// name left to dialog default that is not an identifier

// after
String name = suggestedName;
if (!PsiNameHelper.getInstance(project).isIdentifier(name)) {
  name = "param"; // fall back to a safe identifier
}
// then invoke the refactoring with the corrected name

com.intellij.psi.PsiNameHelper helper = com.intellij.psi.PsiNameHelper.getInstance(project);
if (!helper.isIdentifier(parameterName)) {
  // fix or reject the name before invoking Introduce Parameter
  parameterName = "param";
}

When it happens

Trigger: Calling the Introduce Parameter refactoring (Refactoring | Introduce Parameter) and confirming the dialog while the name field contains a non-identifier string: a keyword ('class', 'int'), a name starting with a digit ('1value'), empty text, or characters illegal at the current language level (e.g. 'my-param').

Common situations: Typos in the name field, names pasted with whitespace or dashes, using a Java keyword as a parameter name, or relying on identifiers with underscores/Restricted keywords that are invalid at the source level configured in the module.

Related errors

• '' '' is invalid extracted class name
• '' '' is invalid field name for delegation
• '' '' is invalid inner class name
• '' '' is invalid parameter class name
• replace.constructor.builder.error.invalid.field.name

AI-assisted analysis of JetBrains/intellij-community@be881553f2 (2026-08-14). Data as JSON: /api/errors/0546c8df4e619256. Report an issue: GitHub.

Appendix: source

Thrown at java/java-impl-refactorings/src/com/intellij/refactoring/introduceParameter/IntroduceParameterDialog.java:302

      myCbCollapseToLambda.isVisible() && myCbCollapseToLambda.isSelected(), selectedType, myPanel.getParametersToRemove());
    invokeRefactoring(processor);
  }


  private void updateFinalState() {
     if (myHasWriteAccess && myCbDeclareFinal != null) {
       myCbDeclareFinal.setEnabled(!myPanel.isReplaceAllOccurences());
       if (myPanel.isReplaceAllOccurences()) {
         myCbDeclareFinal.setSelected(false);
       }
     }
  }

  @Override
  protected void canRun() throws ConfigurationException {
    String name = getParameterName();
    if (!PsiNameHelper.getInstance(myProject).isIdentifier(name)) {
      throw new ConfigurationException(RefactoringBundle.message("refactoring.introduce.parameter.invalid.name", name));
    }
  }

  public void setReplaceAllOccurrences(IntroduceVariableBase.JavaReplaceChoice replaceChoice) {
    myReplaceChoice = replaceChoice;
    myPanel.setReplaceAllOccurrences(replaceChoice.isAll());
  }

  public void setGenerateDelegate(boolean delegate) {
    myPanel.setGenerateDelegate(delegate);
  }

  private class IntroduceParameterSettingsPanel extends IntroduceParameterSettingsUI {
    IntroduceParameterSettingsPanel(PsiLocalVariable onLocalVariable,
                                           PsiExpression onExpression,
                                           PsiMethod methodToReplaceIn, IntList parametersToRemove) {
      super(onLocalVariable, onExpression, methodToReplaceIn, parametersToRemove);
    }

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