"Senior software engineers are the most experienced member of a software team and usually carry the most responsibility and authority of that team. Because of this, interviews will be designed to find candidates who have expert knowledge of the field and years of experience as a software engineer. Expect to be asked tough technical questions and to give examples of previous projects that you have worked on."
Can you have more than one instance of a singleton class within a JVM?
No - "A Singleton is an object that cannot be instantiated. There can be only one instance of a singleton created by the Java Virtual Machine (JVM)."