No, one of the constructors for String takes only char[] as a parameter. You can pass in an arbitrary array of chars, even invalid UTF-16. You're correct that

No, one of the constructors for String takes only char[] as a parameter. You can pass in an arbitrary array of chars, even invalid UTF-16. You're correct that well-written code should never do this. However, there is no guarantee that some library you're using doesn't. You can never assume that 'new String(oldString.getBytes("UTF-8"), "UTF-8").equals(oldString)', which has some unfortunate side-effects if you're doing anything involving serialization and equality. I agree that Java's String API is generally quite well-designed, but the ability to access the raw UTF-16 is a very big leak in the abstraction.