CharNotNumeric

Correction

Here is what's right.

In Java, values of type char are characters, but at the same time they can be seen as unsigned 16-bit integer numbers.

'A' + 1 == 'B'

Value

How can you build on this misconception?

The char type in Java provides a leaky abstraction. It claims to represent an individual character. At the same time, it lets shine through some of the underlying representation: charactes are encoded as numbers (in Unicode). This may be convenient in some situations, e.g., to use a loop to fill an array with the 26 letters of the English alphabet (for (char c = 'A'; c <= 'Z'; c++)), to translate between lowercase and uppercase letters (c + 'A' - 'a'), or to implement a Cesar cipher (c + shift). These uses seem to be common in educational code snippets (maybe due to their cleverness), but they seem less common in programming practice, because they can be error-prone (e.g., they easily break for non-English languages).

It might have been a better language design to treat char as just a character type, and to not imbue it with arithmetic operations. Thus, a student with this misconception may simply see Java as a cleaner language than it actually is.