Suppose the Locale set is de_DE to load a ResourceBundle and default Locale is en_US, and baseClass is BundleName. While loading a ResourceBundle, it looks for the BundleName_de_DE.properties in CLASSPATH, which is not existing. And instead it finds BundleName_en_US.properties in the PATH, so it loads BundleName_en_US.properties file. How to check that required file not found and hence different one is used???