Left Hand Side of an Assignment must be a Variable CharAt

So, the reason why

if (user.charAt(counter) = "") 

gives that error is that “=” is an assignment operator in java, and so the left-hand side must be a variable. That being said, you probably actually want

if (user.charAt(counter) == ' ')

which uses the comparison operator (==) and the space character (‘ ‘). (“” is an empty string)