When should I use the dollar symbol ($) in a variable name?

java, naming-conventions

Solution

From the Java Language Specification on identifiers:

The `$` character should be used only in mechanically generated source code or, rarely, to access pre-existing names on legacy systems.

Problem

The dollar symbol ($) is a valid character to name a variable, e.g. `String superSecretFormula$;`, but when we're talking about naming conventions, when should I use this symbol? Underscore for example is mostly used to separate words, as blank spaces can't be used.

Original source

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