boolean (final String inputString) { final String newPropertyName = myPrefix == null ? inputString : (myPrefix + mySeparator + inputString); final ResourceBundle resourceBundle = myResourceBundleEditor.getResourceBundle(); for (final PropertiesFile propertiesFile : resourceBundle.getPropertiesFiles()) { IProperty key = propertiesFile.findPropertyByKey(newPropertyName); if (key != null) { Messages.showErrorDialog(ResourceBundleEditorBundle.message("already.exists.warning.message", newPropertyName), ResourceBundleEditorBundle.message("new.property.action.text")); return false; } } return true; }