Is it proper way to set names of some variables using $ char?

Question

While I was going through one project I found some strange variables names. Sonarqube gaves me Code Smell statements about these variables.

For example protected String value$editedby$java$lang$String;

And message from Sonarqube:

Rename this field "value$editedby$java$lang$String" to match the regular expression '^[a-z][a-zA-Z0-9]*$'.

So is it proper way to use $ in variables names?

Related: http://stackoverflow.com/questions/7484210/what-is-the-meaning-of-in-a-variable-name — Maroun, Jan 02 '17 at 15:34
You might wanna ask this question on Code Review network rather than StackOverflow... — radoh, Jan 02 '17 at 15:35
[http://stackoverflow.com/a/7484245/348975](http://stackoverflow.com/a/7484245/348975) explains why you should not use `$`. It is largely bullshit in my opinion - if you are not supposed to use `$` why is it an allowed character. On the other hand there is no strong compelling reason to use `$` and it is commonly accepted BS - so I follow along. — emory, Jan 02 '17 at 15:35

score 4 · Accepted Answer · answered Jan 02 '17 at 15:39

I would strongly recommend against it, JLS-3.8. Identifiers says (in part)

The "Java letters" include uppercase and lowercase ASCII Latin letters A-Z (\u0041-\u005a), and a-z (\u0061-\u007a), and, for historical reasons, the ASCII underscore (_, or \u005f) and dollar sign ($, or \u0024). The $ sign should be used only in mechanically generated source code or, rarely, to access pre-existing names on legacy systems.

score 1 · Answer 2 · answered Jan 02 '17 at 15:35

1

While it's technically legal to use the $ character in variable names, Java's coding standard discourages this. The usual convention for variables is lowerCaseCamelCase. So, in your case:

protected String valueEditedByJavaLangString;

answered Jan 02 '17 at 15:35

Mureinik

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score 1 · Answer 3 · answered Jan 02 '17 at 15:39

Camel case is recommended with a lowercase first letter. Variable names should not start with underscore _ or dollar sign $ characters, even though both are allowed.

I would add that the $ character is traditionally used by the compiler in the name of generated class file for inner class.

Is it proper way to set names of some variables using $ char?

3 Answers3